Step 1

Preheat oven to 350°F and grease a 9x9-inch baking pan or line it with parchment paper and set aside.

Step 2

Mix together cake mix, vegetable oil, milk, egg, and vanilla extract. The batter should be well mixed but it will be stiff.

Step 3

Transfer batter to the prepared baking pan and spread evenly with a rubber spatula. If desired, spread more sprinkles on top of batter.

Step 4

Bake for 25-30 minutes, or until a toothpick inserted in the center comes out clean. Cool completely before cutting blondies into 9 squares.