For the filling:
- Around 5 pounds of crisp, tart apples
- 2 tablespoons white sugar
- 1-2 teaspoons cinnamon
- 1 to 1 1/2 cups water
For the crumble:
- 1 cup (2 sticks) melted butter
- 1 1/2 cups packed brown sugar (348 grams)
- 2 cups whole wheat flour (295 grams)
- 2 1/3 cups oats (270 grams)
- Preheat the oven to 350 degrees Fahrenheit.
- Peel the apples if desired. Cut the apples into 1/4 to 1/8 inch thin slices. The thicker the slice, the (slightly) longer the slices should be cooked in the next step.
- In a large pot on medium-high heat, add the water, the apples, the tablespoon white sugar and 1 teaspoon cinnamon. Mix, cover and allow to cook until the apples begin to barely soften. Once the water begins to boil or simmer, reduce the heat to medium. Cook up to 30 minutes, depending on the desired texture. The longer the cook time, the gooeyer the filling.
- While the apples cook, melt the butter. In a medium-large bowl, mix the melted butter, brown sugar and flour. Mix in the oats.
- Push enough of the crumble mixture into the bottom of a 9×13 pan to cover the bottom, with a little creeping up the sides. Lightly pat it down to make the crust. Bake the crust at 350 degrees for 10 minutes.
- Pour the mildly-to-majorly cooked apples on top of the hot crust. The apples will hiss a little bit. Cover the apples with the rest of the crumble mixture and lightly pat down.
- Bake for 40-45 minutes at 350 degrees.