Heat oven to 350°F. Grease bottom and sides of 15x10x1-inch pan with shortening or spray with cooking spray. In large bowl, mix cake mix, pie filling, eggs and chocolate chips with spoon. Pour into pan.
Bake 28 to 38 minutes or until toothpick inserted in center comes out clean. Cool completely, about 1 hour. Spread with frosting. For bars, cut into 8 rows by 6 rows.