Wash and dry the apples thoroughly. Remove any stems and insert wooden skewers or popsicle sticks into the top center of each apple. Set them aside on a tray lined with parchment paper or lightly coated with cooking spray.
In a heavy-bottomed saucepan, combine sugar, corn syrup, and water. Stir over medium heat until the sugar dissolves completely.
Insert a candy thermometer into the mixture and let it cook without stirring until it reaches 300°F (hard crack stage). This should take about 20 minutes.
Once the mixture reaches the desired temperature, remove it from heat and stir in vanilla extract and red food coloring, if desired. Be cautious; the mixture is extremely hot.
Carefully dip each apple into the hot candy mixture, turning and swirling to ensure an even coating. Allow any excess to drip off back into the saucepan.
Place the coated apples back onto the parchment-lined tray. If you'd like to add decorative touches, now's the time—sprinkles, crushed cookies, or edible glitter can be a fun addition. Allow the candy coating to cool and harden completely.
Once the candy coating has set, your homemade candy apples are ready to be devoured. Enjoy the irresistible combination of crunchy, sweet candy and the juicy apple beneath.