Place the granulated sugar and ground cinnamon into a bowl. Stir them together using a fork or small whisk until they are well blended and there are no clumps. For a more pronounced cinnamon flavor, add another 1/2 tablespoon of cinnamon (or to taste).
Pour the cinnamon sugar into an airtight container. Keep it in a cool, dry place, and it will last for several months.