In a large bowl, use a hand mixer or stand mixer to beat the butter and eggs together.
½ cup unsalted butter, 2 large eggs
Add the cake mix and flour. Mix until well combined.
16.25 ounces white cake mix, ¼ cup all-purpose flour
Set aside 2 tablespoons each of semisweet chocolate chips and white chocolate chips. Stir the remaining chips and sprinkles into the cookie dough.
¼ cup rainbow sprinkles, ¾ cup semisweet chocolate chips, ¾ cup white chocolate chips
Tightly cover the dough and refrigerate for 1 hour. While the dough chills, preheat oven to 350°F. Line 2 baking sheets with parchment paper and set aside.
Remove the chilled cookie dough from the refrigerator. Working in batches, use a cookie scoop to scoop 2-tablespoon-sized dough balls onto the prepared baking sheets, making sure to place them at least 2 inches apart. Refrigerate any remaining dough while the first batch of cookies bake.
Press the reserved chocolate chips into the tops of each cookie - do not flatten the cookie dough balls.
Bake for 12-13 minutes, or until the edges are set and the bottoms are lightly browned.
Let the cookies cool on a baking sheet for 10 minutes before transferring to a wire rack to cool completely.