Daring Bakers - Karl-Gustav cake, a Prinsesstårta variation

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I am a bit late with the post of this month's challenge, but as the saying goes ... better late than never, right? :o)

Korena of Korena in the Kitchen was our May Daring Bakers’ host and she delighted us with this beautiful Swedish Prinsesstårta!

I never heard of Prinsesstårta before this challenge, even though we spent a whole week in Stockholm last year.  I feel like I missed out on a great foodie experience, because this cake is truly delicious.  Another reason to go back to the lovely Swedish capital?

It is generally accepted that the original Prinsesstårta was created in the 1930s by a Swedish home economics teacher named Jenny Åkerström, who taught the three Swedish princesses of the time. She published a series of four cookbooks called “The Princess Cookbooks” and in one of the editions, there was a recipe for “Grön Tårta” (green cake). One story is that this later became known as “princess cake” (prinsesstårta) because the three  princesses (Margaretha, Märtha and Astrid) are said to have loved it so much.

By the way, for your trivia knowledge, one of those princesses, Astrid, married in 1926 the Belgian Crown Prince Leopold and later became Queen of Belgium, when Leopold succeeded to his father (when the latter died in a tragic mountaineering accident in 1934).  Queen Astrid was very loved in Belgium and when she died prematurely in a car crash only a year later, the country mourned the lovely queen who left three young children behind.  She is the mother of our previous and current monarch and considering the link between this cake, the princess, the queen and my country; I could not pass on this challenge.

The original Prinsesstårta is characterised by layers of sponge cake, raspberry jam, custard, whipped cream and a (bright) green marzipan coating.  I was already considering alternatives for the raspberry jam (as raspberries are along with cherries, the only red fruits that I can't bring myself to eat) when I came across this little sentence on the Challenge Sheet, under the "Variations" heading :

Karl-Gustav tårta, made with custard, sliced banana, a chocolate-covered meringue disc replacing the middle layer of cake, and covered with yellow marzipan

Whipped cream and banana?  Can you think of a better sounding combo?  At that moment I knew what cake I would make for Mother's Day : a Karl Gustav cake. :o)  I used part of the recipe provided on the challenge sheet and the recipe on Camilla Jakobsson's blog En konditors bekännelser for this Challenge.

My cake ended up to be slightly too big, because I didn't have a small enough round spring form to bake the sponge cake.  I had to use the 26cm form which really is oversized for this cake, considering all the things that go into it.  I'd really recommend using a 20 or 22 cm form, unless, like me, you can rely on willing neighbours and a dozen coworkers to finish off this huge 26cm cake. :o)

The custard, sponge cake and meringue are to be prepared a day ahead, so that the day you are serving the cake you'll only have to take care of the whipped cream, marzipan and the actual assemblying of the cake. I am putting the recipes below, but for good visual step by step pictures, you should look at the Challenge Sheet.

Vanilla custard - Ingredients :

* 240ml heavy cream, divided
* 4 egg yolks
* 2 tablespoons potato starch
* 2 tablespoons granulated white sugar
* 1 vanilla bean, split and scraped 

Directions :

In a medium bowl, whisk together the cornstarch, sugar, and egg yolks. Gradually whisk in 120 ml of heavy cream until smooth.

Meanwhile, in a medium saucepan over medium heat, combine the remaining 120 ml of heavy cream and the scraped vanilla bean and bring just to the boiling point. Remove the vanilla bean pod, leaving behind the seeds. Slowly whisk the hot cream into the bowl with the egg mixture to temper the eggs.

Pour the mixture back into the saucepan and cook over medium-low heat, whisking constantly, until it becomes thick like pudding and just comes to a boil. The mixture must hit a boil for the starch to properly thicken the custard, and also to cook out any starchy taste. If it starts to look curdled or lumpy, remove it from the heat and whisk vigorously until smooth, then return to the heat. As soon as it comes to a boil, remove it from the heat.

Pour the custard into a clean bowl and press a piece of plastic wrap directly onto the surface to prevent a skin from forming. Refrigerate until completely cold.

Sponge Cake - Ingredients :

* Fine dry breadcrumbs for the pan (such as crushed panko)
* 4 large eggs, at room temperature
* 200g granulated white sugar
* 65g all-purpose flour
* 65g  potato starch
* 1 teaspoon baking powder
* 1/8 teaspoon salt

Directions :

Preheat the oven to 180°C with a rack in the lower third of the oven. Thoroughly butter a round springform pan (preferably 22cm, mine was 26cm), line the bottom with a circle of parchment paper, then butter the paper. Dust the buttered pan with enough breadcrumbs to coat the bottom and sides, just like flouring a cake pan. Set aside.

Place the eggs and granulated white sugar in a mixing bowl and beat on medium-high speed with an electric mixer or stand mixer with whisk attachment until the eggs are tripled in volume and very light coloured and fluffy, about 5 minutes. The mixture should fall from the beaters in thick ribbons. Don’t overbeat the eggs – once they form thick ribbons and stop growing in volume, stop beating.

Sift the all-purpose (plain) flour, potato starch, baking powder, and salt into a bowl, then sift the flour mixture over the whipped eggs. With a balloon whisk, fold the flour into the eggs until blended, keeping as much air in the batter as possible. Use large, gentle yet confident strokes, bringing batter from the bottom of the bowl to the top. Once mixed, the batter should be quite thick and smooth.

Pour the batter into the prepared pan, spread it out evenly, and bake in the lower third of the preheated 180°C oven for about 40 minutes or until golden brown on top, springy to the touch, and a toothpick inserted in the center comes out with a few moist crumbs sticking to it.

Let the cake cool in the pan for a few minutes then run a knife around the edge and remove the sides of the springform pan. Don’t worry if it sinks a bit in the middle.

Invert the cake onto a cooling rack and peel off the parchment paper. If the cake is lopsided, press gently to make it level, then allow it to cool completely before continuing. The cake can be made a day ahead and stored, well-wrapped in plastic, at a cool room temperature.

Chocolate covered meringue disk - Ingredients

* 150g whites (I used the 4 remaining from the custard)
* 150g granulated white sugar, divided
* 75g confectioner's sugar
* 1,5 tsp of lemon juice
* 50g dark chocolate pellets
* 40ml of heavy cream

Directions :

Preheat the oven to 90°C.

Beat the egg whites and lemon juice until it begins to foam. Then add 75g granulated sugar and beat on medium-high speed.

Sprinkle the remaining 75g of granulated sugar into the mixture while the whites are being whipped.  Continue to whip until you have stiff peaks.

Sift the confectioner's sugar and mix gently.

Pipe a round disk the size of your baked sponge cake on oven tray lined with parchment paper. I noticed that my sponge cake shrank and was therefore smaller than the 26cm of the baking form.  As the disk should be the same size as your cake, check your cake's diameter before piping.  I have parchment paper which has different cake sizes printed on them, but if you don't, you can always draw the required diameter on your paper and then turn it around before piping, so your food doesn't come in contact with the ink or pencil.

Bake in the oven for about 1 hour and leave overnight in a closed oven .

After removing it from the oven the next day, you can start coating it with chocolate. Because I found the meringue a bit too fragile to turn around (due to its size), I only coated one side, but you can of course do both.

Put your chocolate pellets in a bowl. Heat up the cream to near boiling point (on the fire or microwave it as I did) and pour the simmering liquid over the chocolate, whisking gently all the while until the chocolate has melted completely. Allow to cool slightly.

After the chocolate has cooled down and before it hardens, cover the meringue disk by gently brushing the chocolate over it and allow to set.

Marzipan Covering and Rose - Ingredients :

* 300g marzipan (homemade or storebought, like mine)
* yellow, green and red food colouring
* confectioner's sugar

Set aside a small amount of plain marzipan (about the size of a walnut) for decoration. Knead the remaining marzipan on a surface dusted with confectioner's sugar until it becomes softer and smooth (the warmth from your hands will help this).

Add a small amount of yellow food colouring (I used 3 drops of liquid food colouring) and knead it into the marzipan to get the desired shade of yellow.  The liquid food colouring makes the marzipan really sticky, so you will probably have to incorporate quite a bit of confectioner's sugar to get it workable and less sticky.  Considering you are working with food colouring, it might be a good idea to put on some thin throwaway latex gloves.  Looking at how stained they were when I finished, I was glad I hadn't been working barehanded! Wrap tightly in plastic and refrigerate until you are ready to cover the cake (or store as directed on the marzipan package).

To make the leaves and rose, take the reserved plain marzipan and divide it in 2, about 1/4 for the leaves and 3/4 for the rose.  Taint the marzipan respectively with green and red food colouring. Dust your work surface with confectioner's sugar and knead in the colouring and sugar until it is less sticky.

Roll out the green marzipan between two sheets of wax paper to a thickness of about 2-3 mm and cut out 2 leaf shapes, either using a leaf cutter or by hand as I did.  To reproduce the nerve pattern on the marizpan leaf, I used a real mint leaf that I pressed into it.  It gives a nice pattern to your marzipan if you don't have the specialist leaf cutter.

Roll out the red marzipan between two sheets of wax paper to a thickness of about 2-3 mm and cut out 5 rounds of equal shape using a cookie cutter. Thin the edges of the round slightly using the back of a teaspoon. Roll the first petal into a tube and flare the edges, Wrap the second petal around it, centring it on the crease. Flare the edges and proceed with the same way with the remaining petals until your rose is formed.

Set aside to dry slightly.

Assembling the Karl-Gustav tårta - Ingredients

* 500 ml heavy cream, chilled
* granulated white sugar, to taste (scant 1 tablespoon is plenty)
* Sponge Cake, cooled
* 1 banana, sliced
* 1 meringue disk, covered with chocolate
* Vanilla Custard, chilled
* Marzipan Covering and Rose
* Confectioner's sugar, for rolling and dusting

In a large bowl, whip the heavy cream until soft peaks form. Add sugar to taste (keep in mind that the rest of the cake components are sweet, so the whipped cream should be very lightly sweetened at most) and continue whipping the cream until stiff. You want it to be sturdy enough to provide structure to the cake, but not over-whipped enough to make butter. Multi-tasking is not recommended during this step.  I was preparing dinner while whipping the cream and unfortunately I ended up with butter :o(  I had to drive 30k to the only store I knew to be open on a Sunday in order to buy fresh cream.  So keep your eyes on the cream ! :o) Set the whipped cream aside.

With a long serrated knife, slice the sponge cake into two even layers. This cake is very delicate, so do this as carefully as possible. Use a gentle sawing motion to move the knife through the cake instead of trying to pull it through the cake. Use a spatula to help you lift off the top layer after you cut it. This will become the top layer of the assembled cake.

Place bottom layer on a cake board or serving platter and spread it evenly with the half the chilled custard, leaving enough room around the edges so that it doesn’t spill over.  Spread the banana slices over the custard, leaving at least 1 cm free from the edge of the cake.  Spread part of the whipped cream over the banana slices.

Carefully deposit the meringue disk on top of the whipped cream. Spread or pipe the remaining custard evenly over it, again leaving some room around the edges.

Reserve ½ cup of the stiffly whipped cream. Pile the rest into a mound on top of the custard. Spread it into a thick layer with a thin, flexible spatula or off-set spatula, then hold the spatula at an angle to shape the whipped cream into a dome, piling it up in the middle of the cake as much as possible.

Place the final layer of sponge cake on top of the whipped cream, with the soft inner side facing outwards. Do not press on the top of the cake instead, gently tuck the edges of the cake layer into the whipped cream, so that they are flush with the cream. This will create a smooth, seamless dome on top of the cake.

Gently spread the reserved ½ cup of whipped cream over the entire cake to fill in any cracks and even out the surface. If necessary, refrigerate the cake to firm it up before continuing.

Dust your work surface with confectioner's sugar and press the marzipan into a 20 cm disc (knead it a bit to warm it up first). Coat both sides with confectioner's sugar and roll it out into a 45 cm) diameter circle less than 3 mm thick. Use plenty of icing sugar to prevent it from sticking. Alternatively, you can roll the marzipan out between two wide sheets of parchment paper (still use plenty of confectioner's sugar).  These are the measurements I used for my oversized cake.  If you stick to a 22 cm sponge cake mould, 35 cm should be enough.

Use the rolling pin to drape the rolled-out marzipan sheet over the cake and smooth it around the cake gently with your hands.

If it seems like it wants to fold or buckle around the cake, gently lift and stretch it away from the cake with one hand while smoothing it down with the other. Trim the excess marzipan from the bottom of the cake with a paring knife or spatula blade.

Dust the cake with confectioner's sugar, then place the marzipan rose and leaves in the middle of the cake.

To serve, cut the cake into wedges with a large, sharp knife (run the blade under hot water and wipe it clean after every cut for neater slices). The cake can be served immediately but will be easier to slice after chilling in the refrigerator for at least an hour.

Dared to bake a Prinsesstårta. Challenge accepted !