Apple Filled Hazelnut Cake

Preheat the oven to 180°C (approximately 350°F). Grease and flour a 24 cm (approximately 9 1/2-inch) springform pan.

In a saucepan, melt the butter over low heat. Separate the eggs. In the bowl of an electric mixer, beat the yolks and sugar until light and fluffy.

Sift the flour over the egg yolk mixture and fold in along with the hazelnuts. Fold in the melted butter.

In a separate bowl, beat the egg whites until stiff. Gently stir one-third of the egg whites into the egg yolk mixture to loosen it. Gently fold in the remaining egg whites.

Scrape the batter into the pan and bake until golden brown and a toothpick inserted in the center of the cake comes out clean, about 40 minutes. Loosen the sides of the pan, remove and cool the cake on a wire rack.

For the vanilla glaze: Stir together the vanilla custard powder, a little of the milk to moisten and the sugar. In a saucepan, bring the remaining milk to a simmer, stir in the moistened powder and cook according to package directions. Let cool, stirring often to prevent a skin from forming. Beat the butter with the powdered sugar until creamy and mix with the pudding until well combined.

For the filling: Peel, halve, seed and grate the apples.  In a saucepan, melt some butter, add the powdered sugar and cook until caramelized. Add the apples and sauté about 2 minutes, stirring all the while.