For the chocolate cake:
Preheat the oven to 180°C/350°F. Place a rack in the center of the oven.
Coat a large ring cake tin with a nonstick cooking spray and dust with some flour.
Combine the flour, cocoa, sugar vanilla and ¾ cup sugar.
In a large bowl, beat the egg whites with an electric mixer for 1 minute until foamy. Add the remaining sugar (3/4 cup) to the egg whites and continue beating until whites hold soft peaks.
Add the flour mixture, to the egg whites, one third at a time, and mix until the batter is fully incorporated.
Spoon the batter into the cake tin and bake for 40-45 minutes, or until you insert a skewer in the center of the cake and it comes out clean. Remove from the oven and set aside to completely cool down.
Convert the cake to a flat dish.

To prepare the mascarpone cheese filling:
In a bowl, beat the heavy cream and sugar with an electric mixer until soft peaks form. Gently fold in the mascarpone cheese just to incorporate. Refrigerate.

Cut 2.5cm/1 inch slice horizontally off top of the cake.
Tear out some of the sponge cake, creating a tunnel and leaving 2.5cm/1 inch shell on the bottom.
Spoon the Nutella evenly in the tunnel and cover with the mascarpone cheese filling.
Replace the top of the cake on top.

For the glaze on top:
Add the chocolate, milk to a saucepan,put the sauce pan in a bigger pan full of water and heat it up, whilst whisking dark and milk chocolate together.
Drizzle the glaze on top of the cake.

Then sprinkle the dried raspberry over the chocolate glazing.