This was a cake for my husband's birthday. I wanted to experiment with a cake like this, so his birthday was a good time to try it out. Each letter was cut out of a one layer 8 inch square cake. I crumb coated them in buttercream icing and added the m&m's. They have to be added while the icing is still soft, though, so that they'll stick. I found myself having to re-apply icing in several spots because it had dried by the time I got to it. I found that using four colors gave the most pleasing pattern (for my taste). I thought it would taste a little strange, eating all those m&m's with a bite of cake, but it actually tasted pretty good. I was pleasantly surprised.