Wash and dry the apples and remove the stems. Insert wooden apple skewers into each apple about halfway through. Line a baking sheet with parchment paper.
Microwave the chocolate in a large microwave-safe bowl for 30 seconds, then stir. Continue heating in 10-second increments, stirring after each increment, until the chocolate is melted (be careful not to burn the chocolate). Add the food coloring and stir the chocolate until smooth and well incorporated.
Place a wide bowl next to the prepared baking sheet. Dip the apples in the chocolate and roll to coat. While the chocolate is still wet, sprinkle the sanding sugar over the apples to cover entirely, working over the wide bowl to collect any excess. Place the apples on the baking sheet to harden, about 1 hour.