Using a large serrated knife, slice a thin layer off the tops of the cakes to create a flat surface. Place 1 cake layer on your cake plate. Evenly cover the top with frosting. Top with 2nd layer of cake and evenly cover the top with more frosting. Top with the third layer of cake. Spread the frosting all over the top and sides using a bench scraper or offset spatula.
Decorate with garnishes such as whole or ground pistachios, berries, or edible flowers. Refrigerate for at least 30-45 minutes before slicing.