Stir in nuts, if using, and chocolate chips. Divide the batter evenly among the prepared pans. Bake for 45 minutes to 1 hour or until a toothpick inserted in the center comes out clean. Cool the cakes in the pans for 10 to 15 minutes and then turn out onto a wire rack to cool completely.
For the frosting: Prepare the frosting by whipping the cream cheese, sugar, and vanilla together until creamy. Increase the mixing speed, then slowly pour in the heavy cream and beat until smooth and thick and the frosting is the consistency of whipped cream. Store in the refrigerator until you are ready to use.
To assemble the cake, place 1 cake layer on a cake plate. Spread with 1/2 the container of chocolate-hazelnut spread and top with a thin layer of whipped cream cheese frosting, about 1/2 cup. Repeat with the second layer, using the remaining 1/2 of the chocolate-hazelnut spread and 1/2 cup whipped frosting. Cook's Note: You will use the chocolate spread only for the bottom 2 layers.
Top with the final cake layer and frost or decorate with the remaining whipped frosting. Garnish, as desired.
Cook's Note: There are a couple different things that make this cake above and beyond, but by adding the "secret" ingredient of sour cream to the cake really makes for a much more moist cake. Also I love the sudden surprise of the Nutella in between each layer. For me it brings me back to being a kid and eating chocolate dipped bananas on a stick...known to some as the "Monkey Tail".