Combine Dry Ingredients:

In a mixing bowl, combine the oats, flour, brown sugar, granulated sugar, cinnamon, and salt. Mix well to distribute the ingredients evenly.

Cut in the Butter:

Add the cold, cubed butter to the bowl. Using a fork, pastry cutter, or your fingers, work the butter into the dry ingredients until the mixture forms coarse crumbs. The texture should resemble wet sand with some larger pea-sized pieces of butter remaining.

Top the Apples:

Spread the prepared topping evenly over a baking dish filled with sliced, spiced apples or other fruit.

Bake:

Bake at 350°F (175°C) for 35-40 minutes, or until the topping is golden brown and the fruit is bubbling.