Slice each cake the horizontal way, keeping them as even in width as you can, so you have four cake rounds/layers instead of two. To create a layer cake, we'll frost the top of one cake and then stack another layer on top.
Using a chocolate hazelnut spread, or cream cheese frosting if you prefer, cover the entire top of one layer and then stack another layer of cake on top. Continue this until you've used all four layers of cake. If you're using chocolate hazelnut spread, do not cover the top of the final layer with it, as it will have cream cheese frosting.
Spread the top layer of cake and the sides with cream cheese frosting. You can use however much you prefer- I chose to make mine "naked" style, so more frosting on top, and very thin layer of frosting on the sides.
Using a piping bag and a circular, scoop any remaining cream cheese frosting into the bag, and round tip (or a ziploc bag with a small hole cut in one corner), squeeze and decorate small droplets of frosting along the top outer edge of the cake.
Enjoy! For storing, keep it in the fridge overnight. I feel it's best served at room temp, so take it out of the fridge a few hours before serving to let it warm up. Keep for about 5 days or so.