In a large sauce pan over low heat, melt butter. Add vanilla and stir. Add marshmallows, stir and toss as they begin to melt. Continue to stir. When marshmallows are completely melted add one tablespoon of cake mix at a time, stirring well after each addition. Pour in rice krispies. Stir until coated well. Sprinkle in half of the sprinkles (2 tablespoons). Stir to disperse throughout.
Grease a baking dish with Pam or your favorite greasing method. Spoon rice krispie mixture into prepared pan. Spray your hands with Pam and press down on the mixture to spread out. Sprinkle with remaining 2 tablespoons of sprinkles. Let sit for at least 30 minutes before slicing.