FOR CHOCOLATE CAKE
1 3/4 cups all purpose flour
2 cups granulated sugar
3/4 cup unsweetened cocoa powder
1 1/2 teaspoon baking powder
1 1/2 teaspoon baking soda
1/2 teaspoon salt
2 large eggs
1 cup whole milk
1/2 cup canola oil
1 teaspoon vanilla extract
1 cup hot water
FOR THE HAZELNUT FILLING AND FROSTING
3 cups heavy whipping cream, cold
8 ounces mascarpone cheese, at room temperature
1 cup nutella, hazelnut spread
2 cups confectioner's sugar
1 teaspoon vanilla extract
GARNISH
1/4 cup nutella hazelnut spread
white and dark chocolate shavings, as needed
chopped hazelnuts, as needed