Ruffles Marshmallow Krispie Treats

3 tablespoons butter
4 1/2 cups mini marshmallows
1 teaspoon vanilla extract
6 cups crushed original ruffles chips, crushed {1 8-oz. bag}

Melt butter in large pot over medium low heat. Stir in marshmallows and melt completely. Remove from heat and add in vanilla and crushed chips. Coat completely in marshmallows and pour into greased 9x9 dish. Press to flatten using greased fingers and cool to room temperature. Cut into squares and serve.