Instructions

1. 1
   Melt butter in a medium saucepan over medium heat.
2. 2
   Stir in brown sugar and milk. Bring to a boil and cook only for two minutes, stirring constantly.
3. 3
   Remove from heat. Whisk in peanut butter and vanilla.
4. 4
   Immediately pour over powdered sugar. Beat until smooth with an electric mixer.
5. 5
   Pour in an 8x8-inch pan and cool. Cut into desired shapes.