HEAT oven to 350ºF.
WHISK first 5 ingredients until well blended. Mix flour, baking soda and salt in large bowl. Stir in half the chocolate. Add banana mixture; mix well. Spoon into 12 muffin cups sprayed with cooking spray.
BAKE 20 min. or until toothpick inserted in centres comes out clean. Cool in pan 10 min. Remove to wire racks; cool completely. Meanwhile, beat peanut butter, icing sugar and milk with mixer until well blended. Refrigerate until ready to use.
FROST cupcakes with icing. Top with remaining chocolate.
