In a bowl mix the cubed cold butter, brown sugar, salt, flour, oats, and cinnamon. Use either your hands or a pastry cutter. Once the mixture is combined well and has small clumps, set aside in the fridge for later.
1/2 cup all-purpose flour, 1/4 cup oats, 1/2 cup brown sugar, 1/2 teaspoon cinnamon, 1/2 teaspoon salt, 1/4 cup butter