In the microwave melt:
1/4 c. margarine
1/2 c. peanut butter
1 c. butterscotch chips
Cool this mixture and then pour over an 8 oz. bag of coloured marshmallows. Mix gently until all the marshmallows are coated. Pour into a greased 9x 13 " pan and spread with a spatula. This slice freezes well and is best eaten frozen.