I made these last week for David's birthday since our party was not on his actual day. Recipe is from Real Simple.
1 stick unsalted butter
4 oz. bittersweet chocolate, chopped (or substitute 3/4 c. cocoa, 1/4 c. oil and 1/4 c. sugar)
2 lg. eggs
1 1/2 c. sugar
1 tsp. vanilla
3/4 c. flour
4 lg. peanut butter cups, cut into pieces
Heat oven to 400. Melt butter and chocolate. Stir all ingredients together except peanut butter cups. Fold peanut butter cups in last. Pour into a greased 8x8 pan. Bake about 35 minutes.