Melt 1 cube of butter in microwave.
Stir in 1-2 tsp. vanilla.
Add 16 oz. Kraft marshmallows. Blend and coat with the butter/vanilla mixture.
Microwave in 1 minute intervals until fully melted.
Add 6 cups Rice Krispies and stir well.
Stir in 2-3 cups mini marshmallows.
Blend well and add 4 more cups Rice Krispies.
Spread in a buttered 11x13 pan. The layer will be pretty thin.
Repeat this process 3 times building each layer on top of the first.