1Heat oven to 350°F. Grease 13x9-inch pan with shortening or cooking spray. In small bowl, mix brown sugar and 1/2 cup melted butter until well mixed. Spread evenly in pan. Remove apple cores with melon baller. Place 15 apple halves, cut side down, over sugar mixture in pan. Bake 15 minutes or until bubbling around edges.
2In small bowl, mix flour, baking powder, apple pie spice and salt. In medium bowl, beat 1 cup butter and the granulated sugar with electric mixer on medium speed 3 minutes or until light and fluffy. Beat in vanilla. Add eggs, one at a time, beating until blended. On low speed, beat in flour mixture alternately with milk. Spoon over hot apples in pan.
3Bake 40 to 45 minutes or until apples are tender and toothpick inserted in center of cake comes out clean. Cool 5 minutes. Run knife around edge of pan to loosen cake. Place heatproof serving plate upside down on pan; turn plate and pan over. Leave pan over cake 1 minute so topping drizzles over cake. Remove pan; cool 10 minutes. Cut into squares around apples.