1 box confectioners' sugar
4 tbsp. cocoa
1 stick butter
1/4 c. milk
1/2 c. peanut butter
1 tsp. vanilla

Mix together the sugar and cocoa. Add the butter and milk to the sugar and cocoa and place in a microwave safe dish - do not stir. Place in microwave for 1 1/2 minutes on high, then stir the mixture. Add the peanut butter and vanilla and return to microwave for 1 1/2 minutes more. Remove from microwave and stir well. Pour into a buttered dish and let cool until set.