White chocolate mousse cake with citrus and apple

In an attempt to both improve my French and learn fancy pastry technique, I signed up for a pastry class earlier this year. It was a double success. I understood by far the vast majority of the chat – including jokes! – and learned how to make traditional Belgian pastry (the special cake they make for King’s Day) and all kinds of pastries I drool over in the bakeries.

Everyone at school looked forward to the Tuesday after my pastry classes…

One of my favorites was a delicate white chocolate mousse with citrus (zest and juice) which was so slight and refreshing – and beautiful! You make it in a stainless steel circular ‘pan’ with no bottom (‘cercle inox‘ in French). And the secret is to freeze it for a couple of hours (or overnight) before unmolding it so you get a beautiful mousse finish which looks super professional.


Depending on how high your circle is, you can make two layers of the cake. Mine is relatively short, so I only had one biscuit layer.

So, with no further ado, Acidulé de croquet fondant aux pommes, from Sophie Davin. (Translated by yours truly.)


Cake layer (biscuit au yaourt et au citron vert)

2 eggs, separate

1 plain yogurt (I used a 125 gr yogurt)

90 g sugar

100 g flour

1/2 sachet baking powder (I used 1 1/2 teaspoons)

zest of one lime

Apple layer (palet gélifié à la pomme et au citron)

60 g sugar

50 g water

juice of two lemons

6 g gelatin

2 Granny Smith apples

White chocolate mousse layer (mousse au chocolat blanc et citron vert)

110 g creme fraiche (I used whipping cream)

120 g white chocolate

4 g gelatin

juice of one lime

300 g heavy cream (40% fat content)



First, make the cake layer. Preheat the oven to 180C. Whisk together the yogurt, half of the sugar and the egg yolks. Sift the flour with the baking powder. Fold the flour mixture and lime zest into the yogurt mixture.

Beat the egg whites with the remaining sugar until soft peaks form (en neige). Fold them into the batter.

Spread the batter onto a sheet of baking paper or a silicone baking mat. Be sure the width of the batter is at least the diameter of your circle so you have a good fit. Also, depending on the height of your circle mold, spread your batter thin enough so that you can cut out two circles. Bake the batter for 12 minutes. Allow it to cool before cutting it.

While the cake layer is baking, make the apple layer. Rehydrate the gelatin sheets in a small bowl of cool water. Put the water and sugar in a small saucepan and bring to a boil. Once it boils, dissolve the softened gelatin (squeeze out the excess water before adding it to the sugar syrup) and add the lemon juice. Let it cool slightly. While it is cooling, peel and finely dice the apples, then stir them into the citrus gelatin.

Finally, make the mousse. Rehydrate the 4 g of gelatin in cool water. Chop the white chocolate into rough pieces and place in a heat-proof bowl. Heat the 110 g of whipping cream and pour over the white chocolate. Mix well for a smooth ganache. Once it is smooth but while it is still warm, add the softened gelatin (again, squeezing out the excess water before adding it) and the lime juice; mix well.

In a separate bowl, beat the heavy cream on high until whipped (chantilly souple). Fold it carefully into the white chocolate ganache until it is well incorporated.

Finally, assemble the cake (entremet). Tip: spread a piece of plastic wrap under your circle mold and wrap it around the sides so that you can more easily transport the assembled cake to the freezer. Using your stainless steel circle mold, cut out a piece (or two) of the cake layer to be the exact size of your pan. Place the cake layer in your circle (on top of the plastic wrap), then spread it with about half of your white chocolate mousse. Let it firm up in the freezer for 15 minutes. Then, spread the apple layer over the mousse. Try to spread it evenly and all the way to the sides so that when you unmold it later you can see the delicate green apple dice in the middle of the mousse. If you are making two cake layers, place another layer of cake on top of the apples and, using the palm of your hands, flatten the cake so remove any air pockets. Finish with the remaining white chocolate mousse, spread smooth with an offset spatula. Place it in the freezer for a couple of hours or overnight before unmolding it.

To unmold, carefully remove the plastic wrap from the bottom of your pan. Run a sharp knife (warmed up in a bit of water) around the pan. Use the warmth from your hands to gently lift the pan away.

To serve, decorate with dried apple pieces and lime zest.

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