Make up the cake mix according to manufacturer’s instructions. Measure out 3 pounds batter, deposit 1 pound 8oz into a sprayed and papered 8-inch cake pan. Repeat again times to make 2 cakes total. Bake at 350F until cake springs back lightly when touched. Let cool completely. Once cooled, trim the bellies of each cake, saving them for other uses. Place one cake round on a cake board, and fill with buttercream. Place the other round on top and crumb coat with buttercream. Color additional buttercream green and smooth ice the cake with it. Place green buttercream in a piping bag fitted with a leaf tip and pipe leaves up the side of the cake to resemble a growing garden. Top the cake with lollipops and a “Feliz Cumpleaños” cake topper.