Spray a 9x13 inch pan with cooking spray (you can also line with foil if desired)
In a large pan, melt the butter over medium heat. Be careful not to burn.
Add the mini marshmallows and stir until completely melted. Remove from heat.
Mix in the cereal and then fold in the sprinkles if using.
Transfer mixture to your prepared pan. Smooth with the back of a rubber spatula coated with cooking spray or get your fingers wet and gently press down. The water will help the mixture not stick to your fingers.
Top with additional marshmallows from the cereal and sprinkles to the top if desired.
Cool at room temperature.
Cut into desired size and enjoy!!!
