Spray one 9 x 13 x 2 and one 8 x 8 x 2 pan with non-stick cooking spray.
Arrange half apples in 9 x 13 and other half in 8 x 8. Sprinkle each with 1/2 cup sugar.
Mix together brown sugar, flour, oats, cinnamon, nutmeg, ginger and butter. Stir until well moistened. Sprinkle half this mixture over 9 x 13 apples. Top oat mixture with 1/4 to 1/2 cup caramel.
Bake both pans for 15 to 20 minutes.
Remove from oven.
Arrange apples in 8 x 8 over apples in 9 x 13 (this makes a second layer). Top with remaining oats and another 1/4 to 1/2 cup of caramel. Bake an additional 15 to 20 minutes or till apples are tender and top is crisp. Remove, let sit till warm. Serve with vanilla ice cream and additional caramel sauce on top.