In a large bowl, combine the white cake mix, eggs, vegetable oil, and vanilla extract. Use a mixer or whisk to blend everything together until the dough is smooth. The dough will be slightly sticky, which is perfect for the next step!

Divide the dough evenly into three separate bowls. Leave one portion plain (this will be your “white”), and add red gel food coloring to the second bowl and blue gel food coloring to the third.

Start with a small amount of coloring and mix until you reach your desired shade. Remember, the colors will intensify slightly as they bake.

Cover the bowls with plastic wrap and chill the dough in the refrigerator for 20–30 minutes. This step helps firm up the dough, making it easier to roll into balls.

Preheat your oven to 350°F and line a baking sheet with parchment paper. Take about a tablespoon of dough from each color and roll it into a small ball.

Gently press the three colors together to create a marbled effect. Then, roll the ball in powdered sugar until fully coated.

Place the dough balls about 2 inches apart on the prepared baking sheet. Bake for 10–12 minutes, or until the cookies are set and the tops have that signature crinkled look.

Let them cool on the baking sheet for a few minutes before transferring to a wire rack to cool completely.