In a medium bowl, combine the oats, butter, flour, brown sugar, granulated sugar, and cinnamon. Use a pastry cutter, forks, or your hands to make sure the ingredients are well mixed.. There shouldn't be any dry, sandy patches left in the bowl.
1 cup(s) old-fashioned rolled oats, 8 tablespoon(s) unsalted butter, ½ cup(s) all-purpose flour, ½ cup(s) brown sugar, ¼ cup(s) granulated sugar, ½ teaspoon(s) ground cinnamon