Gather all ingredients and ensure butter is cold from the refrigerator.
In a medium bowl, combine the brown sugar, flour, cinnamon, nutmeg (if using), and salt.
Add the cold, cubed butter to the dry mixture.
Using a pastry cutter, fork, or your fingertips, work the butter into the dry ingredients until the mixture resembles coarse crumbs.
Refrigerate the topping for 15 minutes if you have time – this helps maintain distinct crumbs during baking.
Sprinkle generously over your prepared apple pie before baking.
Bake according to your pie recipe instructions until the topping turns golden brown and crisp.