Heat oven to 180°C.
Beat the eggs and the sugar until pale and dense. Add the mascarpone and the vanilla essence, mix until smooth.
Sift the flour with the baking powder and add into the mixture. Stir until perfectly incorporated, then pour into a 24 cm round cake pan, greased and floured.
Peel and core the apples and arrange them on the cake, as in the first picture. Sprinkle the cake with a few tablespoons of brown sugar.
Bake the cake for about 45 minutes, until golden and dry.
Let it cool down and serve warm, or cold.