Preheat oven to 350°. In a large bowl, combine cake mix, egg, milk and oil (mixture will be thick). Stir in baking chips and jimmies. Spread into a greased 15x10x1-in. baking pan.
Bake 18-20 minutes or until a toothpick inserted in center comes out clean. Cool completely in pan on a wire rack. Cut into bars.
