A charlotte refers to a mousse dessert that is surrounded by a sponge cake. In this instance, the cake is on the bottom, to help create a “cheesecake” look. Marbling the milk and white chocolate fillings really creates a showy dessert that will impress yourself as well as your guests.
Preheat oven to 350 F and line the bottom of a 9-inch springform pan with parchment paper. Do not oil bottom or sides.
Warm eggs in their shells in hot water. Whip eggs and sugar in a mixer fitted with the whisk attachment (or with an electric mixer) for 15 (yes 15!) minutes until it almost triples in volume and holds its shape when you lift the beaters.
Sift flour with baking powder and salt. With mixer on medium low speed, add flour to the egg mixture and blend for 30 seconds. Mix butter and vanilla together and repeat the same way as the flour was added (this avoids tenuous hand-folding).
Scrape batter into prepared pan and bake for 30-40 minutes, until the top of the cake springs back when you lightly press it.
Once cake has cooled, slice horizontally and place bottom half back in the bottom of the springform pan, whose sides have been buttered and lined with parchment. Brush with simple syrup. (top half of cake can be frozen for another day)
Melt milk and white chocolates in separate bowls.
Whisk together egg yolks, sugar, brandy and white wine. Whisk over a pot of simmering water until mixture leaves a ribbon on itself when whisk is lifted. Distribute egg mixture evenly between the 2 bowls of chocolate and whisk in.
Divide mascarpone evenly between the 2 bowls and stir until evenly blended. Fillings will be very glossy and smooth. If they are not glossy and smooth, place the bowl over the pot of simmering water and whisk gently—it should become smooth.
Spoon dollops of white chocolate mixture on top of cake in pan, repeat with milk chocolate mixture, filling in empty spaces. Using a skewer, swirl the two colours together to create a marbled appearance. Chill for at least 4 hours.
Remove springform pan and peel off parchment paper. Press toasted ground nuts or sliced almonds onto side of charlotte. Store loosely wrapped in the refrigerator until ready to serve.