Preheat the oven to 350F and line a baking sheet with parchment paper. Set aside.
In a large mixing bowl, add the cake mix, oil, butter, and eggs. Using a wooden spoon, mix until all ingredients are combined.
Using a cookie scoop, add cookies to the baking sheet spaced 1 1/2 - 2 inches apart.
Bake for 10-12 minutes, until the edges are beginning to brown.
Remove from heat and carefully move the cookies to a wire rack to cool completely.
Once the cookies have cooled, add 1/2 cup of vanilla frosting to a microwave safe bowl. Heat in 10 second increments until completely melted. Stir with a spoon between heating.
Dip one side of each cookie into the melted frosting then add sprinkles before the frosting sets.
Notes
Do not overmix the batter when making the cookies. These cookies are mixed by hand; do not use an electric mixer.If you don’t have funfetti cake mix, you can use a box of white cake mix and add your own sprinkles.