Chocolate Gooey Treat

This recipe was given to me by my sister in law, Alisa. Justin's mom used to make these when they were younger. Oh, they are so yummy. They are pretty much like a chocolate rice crispy treat, but better! The boys LOVED them, can you tell?
3 Tbs. butter
10 oz. marshmallows
Melt the butter in the microwave, then add the marshmallows and melt a little longer. Add:
1 1/2 cups chocolate chips
Mix until melted. Then add:
1 tsp. vanilla
Mix. Add:
1/2 cup chopped walnuts
2-3 cups rice krispies
Spoon onto dish into serving size (2-4 Tbs). Let harden and enjoy. You can freeze these and enjoy them over the next few days!