Marshmallow Peanut Butter/ Butterscotch Bar

2 pkg. butterscotch chips, or peanut butter chips
3/4 cup peanut butter
1/2 cup butter or margarine
4 cups miniature marshmallows (the colored ones are the best)

Place the first 3 ingredients into a microwave safe bowl. Microwave for 1-1/2 minutes, then stir. Microwave for an additional 1-1/2 minutes. Continue at 30 second intervals until melted. Stirring in between each setting. Let cool a couple of minutes and add 4 cups marshmallows and stir well. Pour into a 9 x 13 inch pan and spread evenly. Let cool completely, then cut into squares.