Preheat your oven to 350 degrees

Stir together cake mix, oil, egg, milk and peppermint extract

Split batter, add and mix in M&M's® White Peppermint to one half of the batter and M&M's® Hot Chocolate to the other

Spread batter into greased 9x13 pan w/M&M's® Hot Chocolate on one side & M&M's® White Peppermint on the other side

Bake for about 20-23 minutes or until toothpick inserted into the center comes out clean

Allow pan and bars to cool completely before removing; cut and serve