Preheat the Oven: Start by preheating your oven to 170°C (340°F) with the fan on. This ensures your cake bakes evenly.
Melt the Chocolate: In a microwave-safe bowl or a bain-marie, melt your chocolate. Stir until smooth and set aside to cool slightly.
Beat Eggs and Sugar: In a large mixing bowl, combine the eggs and sugar. Beat them together until the mixture is pale and foamy.
Mix in Mascarpone and Dry Ingredients: Add the mascarpone cheese to the egg mixture and blend well. Gradually add in the flour, cocoa powder, and baking powder, stirring to combine after each addition.
Incorporate Melted Chocolate: Fold the melted chocolate into the batter until well integrated.
Prepare Apples: Peel and core the apples. Slice one apple thinly to line the bottom of your mold and chop the other one into small cubes.
Assemble the Cake: Pour the batter into a prepared cake mold (buttered and floured if necessary) and scatter the diced apples on top.
Bake: Place the mold in the oven and bake for about 45 minutes, or until a toothpick inserted in the center comes out clean.
Cool and Serve: Allow the cake to cool in the mold before transferring it to a wire rack. Once completely cool, slice and enjoy!