Prepare the cake according to the directions on the box. Next, prepare the fluffy boiled icing according to the recipe.
Place a cardboard cake round on a lazy Susan or pizza pan directly in the center. You will be rotating the cake, so make sure it’s centered. Frosting and layering is easier when the cake round is elevated on an inverted bowl or cake stand, but not essential.
First, level your cakes. Place a cake layer rounded side up on the cake round. Hold a serrated knife with the sharp side toward the cake and perfectly level at the edge of the cake where it starts to round higher. Do not move the knife! Instead, rotate the cake with your other hand. As you turn the cake, it will slice into the cake all the way around until you are back where you started. If you were holding your knife level, your knife will slide right into the cut you started with.
Remove the cut part and you will have a flat cake layer! Repeat with the other layer(s) and set the cake aside. The discarded tops will be a great snack later with some pudding or ice cream.
Place 1 Tbsp of icing on the cake round and put the first layer on the cake round. The icing will help stabilize the cake, adhering it to the round. Using a large off-set spatula or a butter knife, drop about 1 cup of frosting in the center of the cake. Push the frosting to the edges, adding more icing if needed. The frosting should go slightly past the edges. You will smooth this out when you do the sides. Rotate the cake as you go.
If this is a 3-layer cake, simply repeat these steps for the middle layer using another cup of icing. For the top layer of either a 2- or 3-layer cake, place the cake upside down. You have leveled your cakes but the underside is smoother and will produce a better top.
You’re now at the part of the process where crumbs will be noticeable, so you’ll use more frosting here. Therefore, drop 1½ cups in the center this time.
After you have covered the top, hold the spatula flat and level against the top of the cake. Rotate the cake but do not move the spatula. If you are holding the spatula flat, you will end up with a smooth top.
Now put as much frosting on the spatula as it will hold and start icing the sides. Hold the spatula flat against the cake with the handle pointing to the ceiling. Be very careful about crumbs. Again, this will be easier with more icing. As you get a section covered, hold the spatula still with one straight edge near the cake and rotate the cake with your other hand.
Repeat until you have covered the sides. Then hold the knife still and rotate the cake to smooth all the way around the cake.
One Last Thing
Place parchment paper between the cake stand and cardboard round so you don’t get the ‘presentation plate’ messy. Just slide the paper out before serving!