Mix together in a saucepan the sugar and cocoa. Add the milk and cook on low until sugar dissolves.
Add the butter and melt into chocolate mixture.
Stir in the peanut butter and remove from heat. Stir together until ingredients are melted and combined together. Add in the vanilla.
Pour mixture over top the rolled oats. Stir until evenly coated. Drop by heaping tablespoonfuls onto wax paper. Let set, and enjoy!
Adapted from My friend, Amanda