Heat a medium size sauce pan to medium low heat, add butter and let it slowly melt. When butter is mostly melted add in the marshmallows and stir them regularly.

When the butter and marshmallows are totally melted add the vanilla extract and sprinkles

Line an 11x9 pan with wax paper, lightly spray with cooking oil and set aside.

Add the cereal to the marshmallow mixture, stir well, and spread into the pan then top with additional sprinkles if desired.

Place in the fridge and let the bars firm up.

When you are ready to cut turn them out onto a cutting board, removing the wax paper and cut into squares.

Store in an airtight container in the fridge.