Step 1

Preheat oven to 350° F.

Step 2

Soften butter in the microwave 10-15 seconds. Combine butter with both light brown sugar and granulated sugar. Mix until smooth and mixture becomes fluffy.

Step 3

Add egg and vanilla extract and beat until egg is thoroughly incorporated.

Step 4

In a separate bowl, combine flour, dry cake mix, oats, salt and baking soda. Slowly add flour mixture to dough batter while mixing at a low speed.

Step 5

Once all the flour has been added, increase speed to medium until dough forms. Add mini chocolate chips. MnMs and sprinkles and mix until combined.

Step 6

Grease a 9-inch spring form pan with Crisco or cooking spray. Line the bottom of parchment paper or tin foil.

Step 7

Bake for 32-35 minutes at 350°F. During the last 10 minutes, cover the cookie cake with tin foil. Remove from oven and allow to cool until removing the edge of the pan.

Step 8

Allow butter to soften for about 30 minutes. Or soften in the microwave for 10-15 seconds.

Step 9

Whip butter with a paddle attachment on medium speed until light and fluffy.

Step 10

Slowly add powdered sugar 1 cup at a time. Frosting will become thick. After powdered sugar have been added, add 1 tablespoon of milk. Whip until smooth. Pipe onto edges of cake and garnish with additional sprinkles.