1/2 cup all-purpose flour
1/2 cup brown sugar
1/2 cup rolled oats
1/2 teaspoon cinnamon
1/4 teaspoon salt
1/2 cup cold unsalted butter, cubed
Mix the flour, brown sugar, oats, cinnamon, and salt in a bowl
Add the cold butter
Rub or cut the butter into the dry ingredients until the mixture looks crumbly
Use immediately or chill until ready to use