Heat oven to 375. Combine flour and powdered sugar in medium bowl. Cut in margarine until crumbly. Press mixture in ungreased 9 inch square pan. Bake for 15-17 min or until lightly browned.
Spread jam evenly over baked crust. In small bowl, beat cream cheese and milk until smooth. Add melted white chocolate to cream cheese mixture; beat until smooth. Drop cream cheese mixture by teaspoonfuls evenly over jam; carefully spread to cover. Refrigerate until set.
In small saucepan over low heat, melt semi-sweet chocolate with shortening, stirring constantly. Spread over white chocolate layer. Cool completely; cut into bars.
Store in refrigerator.
Makes 25 bars.