Divide apples into four, prepared 2-inch quarter steam table pans (2 1/2 lbs each pan).
Sprinkle 3 Tbsp sugar and 2 Tbsp flour over apples in each pan; toss to coat.
Place Krusteaz Professional Muffin Mix and baking powder in mixing bowl. Using a whisk, blend dry ingredients.
Using a spatula, gradually add eggs and stir just until eggs are incorporated. Do not over-mix. Mixture will appear dry and crumbly.
Divide topping over apples in each pan (23 oz each pan).
Drizzle 6 Tbsp melted butter over topping in each pan.
For convection oven, bake at 300°F 35-40 minutes; for standard oven, bake at 350°F 45-50 minutes or until golden brown and apples are tender. Serve with vanilla ice cream, if desired.