1. Wash and dry the apples thoroughly. Insert the wooden sticks into the top of each apple and set them aside on a parchment-lined baking sheet.
2. In a medium saucepan over medium-high heat, combine the sugar, water, and corn syrup. Stir occasionally until the sugar dissolves.
3. Once dissolved, stop stirring and let the mixture come to a boil. If using, add the cinnamon flavoring.
4. Continue boiling the mixture until it reaches 300°F (hard crack stage) on a candy thermometer.
5. Remove the saucepan from heat and let it sit for a few seconds until the bubbles subside. Carefully stir in the black gel food coloring.
6. Quickly dip each apple into the hot syrup, turning to coat it entirely. Let any excess syrup drip off before placing the apple on the prepared baking sheet.
7. Allow the coated apples to cool and harden completely before serving.
