Need a sheet cake and want half of it chocolate and half of it white? No problem! Mix up two cake mixes in separate bowls. Prep sheet pan as usual. Cut a piece of cardboard the same width as your pan. Hold the cardboard at the centre point of your pan while pouring chocolate cake batter into one half of the pan and white cake mix into the other half of the pan. Remove cardboard slowly and gently, pulling straight up. Bake cake as usual.. Voila, now you have a half and half cake.