For coffee cake, place 4 lb (12 cups) Krusteaz Professional Buttermilk Biscuit Mix, water and sugar in mixer bowl.
Using a paddle, mix on low speed 1 minute.
Scrape bowl and paddle. Continue to mix on low speed for an additional 1 minute.
Scale batter into prepared 24 x 16 x 2-inch sheet pan.
Spoon apple pie filling over batter. Set aside.
For streusel topping, place 1 lb (3 cups) Krusteaz Professional Buttermilk Biscuit Mix, brown sugar, butter and cinnamon in mixer bowl. Using a paddle, mix on low speed 2 minutes or until crumbly.
Sprinkle topping over apple pie filling.
For convection oven, bake at 300°F 20-25 minutes; for standard oven, bake at 350°F 30 -35 minutes.