1Heat oven to 350°F. Spray bottom of 13x9-inch pan with cooking spray.
2In large bowl, stir all Cookie Base ingredients until soft dough forms. Press dough in bottom of pan using floured fingers. Bake 15 to 18 minutes or until edges are light golden brown. Cool completely, about 30 minutes.
3In small bowl, stir frosting, milk and peanut butter until well blended. Spread over base. Stir jam; drop by teaspoonfuls over frosting. Swirl jam for a marbled design with tip of knife. Refrigerate 20 minutes or until set. For bars, cut into 9 rows by 4 rows.