With a serrated knife, trim the top of one cake layer to make it level. Place the layer, trimmed side up, on a serving plate. Spread the top with about 1/2 cup of the icing. Place the second cake layer, rounded side up, on top of the first. Using a metal frosting spatula and the remaining icing, spread the icing evenly over the side of the cake. Then spread icing evenly over the top.