Preheat oven to 350 degrees. In small bowl, combine flour, baking powder and baking soda; set aside.
In large bowl, combine butter, cream cheese, sugar and vanilla; beat until creamy. Add egg; beat well. Gradually add flour mixture. Stir in peanut butter morsels. Pour into a foil-lined 9" square pan. Bake for 35-40 minutes. Cool completely before cutting. This makes 16 2 1/4" brownies.