- 1 box white cake mix
- Red, orange, yellow, green, blue, and purple food dye
- 2 cups powdered sugar
- 4 tablespoons milk
- Prepare cake mix according to package instructions.
- Divide batter evenly into 6 small bowls. Color each bowl of batter with food dye. If you don't want to make a rainbow, feel free to use any 6 colors.
- Grease the inside of a slow cooker with cooking spray. Pour cake batter, one color at a time. Bake on high for 4 hours.
- While cake cooks, make your icing. In a large bowl, gradually add milk to powdered sugar and stir until you reach the desired icing consistently. If the icing is too thin, add more powdered sugar. If it's too thick, add more milk.
- After 4 hours, allow cake to cool for 10 minutes. Top with icing, serve and enjoy!