Preheat oven to 350°F. Spray two 9-inch round cake pans with non-stick cooking spray. Line with pre-cut parchment paper (trace shape of pan onto paper and trim to fit in pan). Spray more cooking spray. Set aside.

Prepare cake mix according to package instructions. Fill prepared pans equally with cake batter. Bake according to package instructions. (I used Pillsbury and baked the cakes for 28-30 minutes.) Let them cool. Then cover and put in freezer for 1 hour. You can skip this step, but the cake is much easier to handle when it is chilled and firm.

Meanwhile, scoop the chocolate fudge frosting into a large bowl. Add the butter. With an electric mixer, beat on medium for a minute. Turn mixer to low and gradually add the sugar and cream. Beat for 2 minutes on medium. If it's too thick, add a little more cream. Stir to combine.

Place chilled cake on cake board or large plate. Using a large bread knife, slice horizontally to remove the dome shape of cake. You have a nice flat surface. Frost top of cake. Level second cake and place on top. Frost all over top and sides of cakes.

After unwrapping all of the candy bars, stick Kit Kat's to the sides of the cake, lining them up vertically, side-by-side. If the frosting has formed a crust, just use a butter knife to spread it again, making it sticky. Wrap a bow around the cake, securing the Kit Kat's. Fill the top of the cake with M&M's. You should have about 1 ½ inches of vertical space above the cake to add the M&M's. You might have a few extra left over. I had about ½ cup left over.

I think it's best to keep the cake at room temperature because when the candy gets cold, it will sweat when you take it out of the refrigerator. Store covered for up to 3 days. Or if you must refrigerate, it will last a few days longer. Remove bow before cutting the cake.