Preheat the oven to 350 degrees F.

Peel and core the apples, leaving them whole.

Place them in a casserole dish and brush them with the lemon juice.

Place the apples in the oven and bake for 15 minutes.

Remove from oven and let cool.

Melt the chocolate in the microwave or in a double boiler. Remove from heat and let cool.

Grease and flour a 10-inch springform pan.

Preheat the oven to 350 degrees F.

In a separate bowl, whisk together the flour, cocoa powder, baking powder, and salt.

Beat the butter and brown sugar until creamy.

Add the eggs one at a time and beat in the vanilla extract.

Beat in the melted chocolate.

Add the dry ingredients and beat until just combined.

Spread the cake batter out in the pan. Arrange the Nutella filled apples in the pan, pushing them into the batter.

Heat the Nutella in the microwave or in a double boiler. Stir in the hazelnuts.

Use a small spoon to fill the apples with the Nutella-hazelnut mixture.

Place in the oven. After 40 minutes, cover the pan with aluminum foil and bake an additional 20 minutes.

Remove from oven and let cool. De-pan the cake. Transfer to a serving plate, sprinkle with powdered sugar, cut and serve.