Mimi found this recipe. We adapted it form the original recipe on the back of the cereal box!
COOKIE RECIPE HELP

INGREDIENTS
4 tablespoons unsalted butter
1 10-ounce bag of mini or regular marshmallows; for best results use a fresh bag
1/3 to 1 cup yellow cake mix or any flavor, such as Funfetti
1 teaspoon vanilla extract

6 cups Rice Krispies Cereal (whole)

1 1.75-ounce container of sprinkles

INGREDIENTS
1. Spray one 13- x 9- x 2-inch pan (thinner version) or 8 x 8-inch pan (thicker version) with cooking spray. Spray a large wooden mixing spoon with vegetable oil. Set aside.

2. On the stovetop, in a large heavy-bottomed saucepan melt butter over low heat.

3. Add marshmallows and cook under low heat, stirring continuously until they begin to melt, adding in cake mix one spoonful at a time so its combined.
Add the vanilla and stir to combine.

Remove from heat.

4. Stir in cereal so it is completely coated with the marshmallow mixture. Sprinkle in half of the sprinkles and mix.

5. Spoon the mixture into the prepared pan, spread evenly.

6. Then, spray your hands with non-stick spray and compress the mixture with your hands.

Press into a baking dish and top with the remaining sprinkles.

7. Let sit for about 20 to 30 minutes  so the mixture can cool and set before cutting.

STORAGE
Store at room temperature for a few days placed in an airtight container.

Enjoy!
mimi