Bake both cakes according to the box directions in 9 inch round pans.
Let the cakes cool completely.
Using a compass, draw a circle with a 3 inch diameter and a circle with a 6 inch diameter onto cardboard or paperboard. I used a brown paper bag!
Cut the circles out!
Once your cakes are cooled, level all four cakes equally using a cake leveler tool or a knife.
From each cake, cut a 6" circle.
Center the 3" paper in the middle of the 6" circle you cut, and cut around the 3" circle. Repeat on each of the 4 cakes.
For each cake, you will have 3 circles.
Construct your first layer on your cake plate, alternating chocolate and vanilla circles.
Add frosting in between each layer to "glue" it together. Continue adding layers. Your next layer should have an outside chocolate circle, continuing to alternate.
I chose to do only 3 layers, but 4 layers are possible. Frost your cake.