Spray a 9x9 inch baking pan with non-aerosol cooking spray.
Combine sugar, cocoa, milk and butter in a saucepan. Bring mixture to a boil. Stop stirring after the mixture starts boiling; allow it to boil for 2 minutes.
Remove mixture from heat and stir in oats, peanut butter and vanilla; mix well. Spread mixture into the prepared pan. Cool and store in refrigerator.
