In saucepan, bring sugar and milk to a boil over medium heat; boil for 3 minutes. Add peanut butter and marshmallow cream; mix well. Quickly pour into an 8-in square pan lined with aluminum foil. Chill until set. Lift out of pan and peel foil down. Cut into squares.

I learned through some trial and error that you need to stir like a maniac in order to keep the bottom from scorching.