1. Line a baking sheet with parchment, and lightly brush parchment with butter. Combine sugar, water, corn syrup, and food coloring in a medium heavy-bottomed saucepan. Bring to a boil, then reduce heat to medium-high. Boil until syrup reaches 300 degrees to 310 degrees (hard-crack stage) on a candy thermometer, about 15 minutes.

2. Meanwhile, insert a wooden dowel into the stem end of each apple, pushing halfway down. When syrup reaches desired temperature, immediately remove from heat. Working quickly, dip apples, 1 at a time, in caramel to coat. Transfer to baking sheet; let cool. Candy apples can be made up to 4 hours ahead; keep at room temperature until ready to serve.