Add Nutella to boiling butter and you'll be amazed by the result

Ingredients:
100g of sugar
30g of cocoa powder
100g of unsalted butter
100ml of water
300g of milk biscuits
2 egg yolks
150g of sugar
1 teaspoon of vanilla sugar
120g of cornstarch
1.2L of milk
200g of unsalted butter
150g of hazelnut cream
200g of semi-sweet chocolate
20ml of vegetable oil
150g of heavy cream