Using a cake leveler, cut the domes off the cake and place one cake slice onto the cake round/serving plate.
Scoop 1 cup frosting onto the cake slice and smooth evenly.
Place a second cake slice on top of the first slice.
Scoop another 1 cup frosting onto the second cake slice and smooth evenly.
Place the last layer of cake slice on top.
Using remaining frosting, frost entire cake.
Drizzle the chocolate ganache all down the sides of the cake.
Pipe dollops of frosting around the top of the cake.
Sprinkle with chocolate sprinkles, if using.