Preheat oven to 180°C/350°F. Grease two 8-inch round pans and line with parchment paper.
Make the apple sponge: Whisk eggs, granulated sugar and light brown sugar until pale, then slowly stream in oil. Whisk flour, cornstarch, baking powder, baking soda and spices in a separate bowl and fold into the egg mixture. Stir in grated apples and lemon juice. Divide the batter into the pans and bake 25–30 minutes or until a skewer comes out clean. Let cool completely.
Caramelise the apples: Melt butter in a saucepan over medium heat. Add diced apples, sugar, cinnamon, ginger, cardamom and a pinch of salt. Cook until the apples soften and turn golden. Let cool completely.
Prepare the mascarpone cream: Beat mascarpone, cream cheese and powdered sugar until smooth. In another bowl whip heavy cream with vanilla extract to soft peaks and fold into the mascarpone mixture. Stir in melted white chocolate and melted butter. Refrigerate.
Assemble the cake: Level the cakes if needed. Place one cake layer on a serving plate, spread over the caramelised apples and half of the mascarpone cream. Top with the second cake layer and frost the top and sides with the remaining mascarpone cream.
Chill the cake for at least 1 hour before slicing. Decorate with extra caramelised apples and enjoy.