Preheat the oven to 350 degrees F. Spray an 11x15 inch jelly roll pan with cooking spray.
Beat sugar, butter, vanilla extract & eggs on low until mixed well. Stir in flour, salt and baking powder. Spread 2/3 of the batter in the pan. Spread pie filling evenly over the batter. Drop the remaining batter evenly in dollops over pie filling. Bake until a toothpick inserted in the center comes out clean (check at about 25 minutes). Mix confectioners' sugar and milk in a small bowl to desired consistency for a glaze (sometimes I make more) and drizzle over the top while still warm.