Pour 5 cups of rice crispy cereal into a large bowl and set aside.
Heat 1/4 butter over low heat in medium sized pan. Once the butter is fully melted add in 6 cups of marshmallows to the pan. Keeping on low heat cook until the marshmallows are fully melted. Add in your vanilla extract and stir until well combined.
Pour the butter and marshmallow mixture over the bowl of rice crispy cereal you set aside earlier. Mix until combined.
Add in your sprinkles and stir to combine.
Pour your mixture into a glass baking dish and spread out over entire dish.
Cut into 12 squares and serve to your preference.