• Make in advance: You can make the cake base and the egg yolk-chocolate filling one day in advance; they both have to be completely cool before finishing the cake.

Cake base:

• Preheat the oven to 180°C/ 350°F. Butter the baking dish and line it with parchment paper.
• Roast the walnuts in a pan until golden and fragrant. Immediately transfer to a large plate and let cool while you beat the egg whites. Chop the walnuts roughly.

  200 g walnuts/ 7 oz
• Beat the egg whites: Separate the eggs. Set the egg yolks aside; you will need them for the buttercream. Beat the egg whites with the salt until stiff. Slowly add the sugar and continue beating until the egg whites are stiff and glossy.

  9 eggs; egg whites + pinch of salt + 150 g granulated sugar/ ¾ cup
• Mix the flour and the baking powder in a small bowl.

  65 g all-purpose flour/ ½ cup + 2 teaspoons baking powder
• Make cake batter: Add the chopped roasted walnuts to the egg whites, sieve the flour mixture on top, and fold everything in the egg whites very gently.
• Bake the cake: Spread the mixture into the prepared pan and bake for 20 to 30 minutes or until slightly golden. Let cool completely, and melt the chocolate for the buttercream, in the meantime, it also has to cool.

Buttercream:

• To make the filling, place the egg yolks, finely chopped milk chocolate, sugar, and cocoa powder in a heat-proof bowl.

  the 9 egg yolks set aside before + 100 g milk chocolate/ 3.5 oz + 200 g granulated sugar/ 1 cup 2 tablespoons unsweetened cocoa powder
• For the bain-marie, choose an appropriate pot, so you can fit the bowl on top. Pour some water into the pot, but make sure that the water doesn't touch the bowl. Put the bowl on top of the pot and warm gently, making sure that the water doesn't start to boil. If it starts to simmer remove from the heat.
• Whisk the egg yolk-chocolate mixture continuously until the chocolate melts completely and the mixture thickens. It will not take very long. Let the mixture cool completely at room temperature.
• Add butter: The butter also has to be at room temperature. Beat the soft butter until pale and fluffy. Slowly start adding the chocolate mixture, one tablespoon at a time, while beating it all the time until everything is incorporated and the buttercream is fluffy.

  250 g unsalted butter/ 1 cup

Ganache:

• Layer cake: Place the base of the cake back into the clean baking dish. Spread the buttercream on top and level nicely.
• Heat heavy cream: Pour the heavy cream into a small pot and bring to a simmer, but don't let it start to boil.

  200 ml heavy cream/ ¾ cup +1½ tablespoons
• Chop the chocolate: In the meantime, chop the chocolate very finely; I prefer to process it finely in the food processor.

  200 g semisweet chocolate/ 7 oz
• Make ganache: Place the chocolate into a bowl and pour the hot heavy cream on top of it. Let stand for 5 minutes, then whisk with the hand whisk until shiny. Make sure is not too hot, you can leave it for a few minutes, then spread the ganache on top of the cake.
• Decorate Queen Mary cake: Sprinkle the cake with silver or chocolate sprinkles or whatever you like. Refrigerate it for a couple of hours to allow it to set, then cut it into pieces.