1/2 c. butter
1 c. sugar
2 eggs
1 c. flour
2 oz. unsweetened chocolate, melted and cooled
1/3 c. chunky peanut butter
1/4 c. miniature semi-sweet chocolate pieces

Heat butter until melted and remove from heat. Stir in sugar and eggs. Beat slightly by hand just until combined; stir in flour. Remove 3/4 c. of batter and set aside. Stir melted chocolate into remaining batter. Spread chocolate batter into a greased 9 x 9 x 2 baking pan; set aside. Stir peanut butter into reserved batter. Dollop on top of chocolate batter, then sprinkle with chocolate pieces. Swirl batter with a knife.

Bake at 350°F for 20 to 25 minutes. Do not overbake.