Cake for a coworker. Cake mixes are Betty Crocker Devil's Food and French Vanilla. Alternate scoops of each batter into two 8" round pans, greased, floured and parchment paper cut to size. Use a long skewer and sweep through the batter (not too much) to create the marbling. Since one box is enough to fill two pans, I used the leftover batter for a 18 cupcakes of vanilla and devil's food to take to work to feed the masses. Buttercream is the new recipe I used for the Pumpkin cake and everyone agreed is much silkier than the buttercream I made before. I wanted so badly to use the rainbow sequins I bought.
12 cups powdered sugar
8 sticks (1 cup) room temp unsalted butter
4 tsp clear vanilla extract
8 tbsp heavy whipping cream
Divide as needed and add food coloring to desired shade.
I made the 1M technique swirls on the cupcakes and topped them and the cake with the rainbow sequins. No pictures of them though.