Insert a stick into the stem end of the apple pushing about halfway through and set aside.
Line a baking sheet with parchment paper and coat generously with cooking spray.
In a large saucepan over high heat, stir together the sugar, syrup and water. Bring the mixture to a boil and turn the heat to medium. Stir in the food coloring. Insert a candy thermometer and continue to boil until the mixture reaches Hard Crack stage (from 300-310 degrees), approximately 15-20 minutes.
Remove the sugar mixture from the heat and allow to rest for a few minutes before quickly dipping the apples in the sugar mixture turning to coat. The rest allows the bubbles to subside a bit so you don't have bubbles in your candy coating.
Transfer to the baking sheet to cool completely.
Video
Notes
Apples can be made up to two days in advance and stored at room temperature.