Add the mascarpone, cold heavy cream, and powdered sugar to a mixing bowl. Whip until smooth and thick enough to spread. Do not overwhip.

Divide the filling into 2 equal parts.

Leave one half plain.

Mix the Nocciolata spread into the second half until smooth.

Pour the coffee into a shallow bowl.

Dip each cocoa biscuit briefly in the coffee and arrange them in a baking dish to make the first layer.

Spread the plain filling evenly over the first biscuit layer.

Dip more biscuits in coffee and arrange them over the white filling to make the second layer.

Spread the chocolate-hazelnut filling evenly over the second biscuit layer.

Dip the remaining biscuits in coffee and arrange them on top to make the third layer.

To make the topping, heat the heavy cream until it just comes to a boil.

Pour the hot cream over the chopped chocolate and let it sit for 2 to 3 minutes.

Stir until the ganache is smooth and glossy.

Pour the ganache over the top layer of biscuits and spread it evenly.

Refrigerate the cake for 2 to 3 hours, or until set.

Cut into squares and serve cold.