1Heat oven to 350°F. Grease bottom and sides of 13x9-inch pan with shortening. In medium bowl, mix butter, granulated sugar, vanilla and egg with spoon. Stir in flour and baking powder until dough forms. Pat dough evenly in pan.
2Beginning 3/4 inch from short side of pan, press 1/2-inch-wide and 1/4-inch-deep groove in dough, using end of wooden spoon. Make 8 more grooves, each 1 1/2 inches apart. Fill each groove with slightly less than 1 tablespoon jam.
3Bake 20 to 25 minutes or until light golden brown. Cool completely, about 1 hour. Sprinkle with powdered sugar. For bars, cut into 8 rows by 4 rows.