1Heat oven to 350ºF. Line 12 regular-size muffin cups with paper baking cups.
2In large bowl, beat granulated sugar, peanut butter, sour cream, egg and egg white with electric mixer on medium speed until well blended. Beat in remaining ingredients except powdered sugar on low speed just until mixed. Divide among muffin cups.
3Bake 15 to 20 minutes or until toothpick inserted in center comes out clean. Remove from pan to wire rack. Cool completely, about 30 minutes. Sprinkle tops with powdered sugar.