Step 1

Preheat the oven to 350 degrees F.

Step 2

Grease a 9x13-inch baking dish with the extra softened butter.

Step 3

In the prepared baking dish, add the apples, 1 cup of the brown sugar, 2 tablespoons of the flour, and 1 teaspoon of the cinnamon, and toss to coat.

Step 4

Scatter 6 tablespoons of the cubed butter on top of the apple mixture.

Step 5

In a large bowl, add the remaining flour, the oats, the remaining brown sugar, the remaining cinnamon, the baking soda, the baking powder, and the salt, and mix until well combined.

Step 6

Add the remaining butter to the oat mixture and cut it in with a pastry blender until the mixture resembles crumbles.

Step 7

Sprinkle the crumbles on top of the apple mixture and the butter in the baking dish.

Step 8

Bake until bubbly and golden-brown, about 45 minutes.

Step 9

Allow the bake to cool, about 15 minutes.

Step 10

Serve.