Preheat oven to 350 degrees F. Grease mini bundt pan and set aside.

Mix together cake mix, water, oil, and eggs until fully combined.

Add 1 1/2 to 2 tbsp of batter to each cake cavity and bake for 15 to 18 minutes.

Remove from oven and let cool for a few minutes before removing. To remove, gently use fingers to twist the bundt cakes to loosen, you make also need to run a tooth pick around the center where the tube pokes up.

Set cakes on a plate or cooling rack and remove the lid and seal from the Pillsbury frosting container, microwave for three 15 second intervals, stirring in between. Drizzle melted frosting over the cakes and sprinkle with rainbow sprinkles.