Thoroughly wash and dry apples. Be sure to remove the waxy coating to help the caramel stick. Remove the apple stem and insert a caramel apple stick into the center of the apple.
Line a baking sheet with a silicone baking mat or grease a pan with butter.
Prepare any toppings you'd like to add to your caramel apples.
Add the heavy cream, corn syrup, brown sugar, butter and salt to a heavy saucepan over medium heat. Stir constantly until the mixture comes to a boil.
Attach the candy thermometer to the side of the pan. Make sure the bulb doesn't touch the bottom of the pan or you'll get an inaccurate reading.
Stop stirring and let the mixture boil until it hits 240 F, be patient.
Remove from heat and gently stir in the vanilla.
Allow caramel to cool for 10-15 minutes until slightly thickened. If caramel is too runny to coat apples, wait 5-10 minutes and try again.
Dip the apples into the caramel, one at a time, letting excess caramel drip off the apple.
Add your toppings after dipping the apple but before the caramel completely sets up.
Notes
This recipe was adapted from Sally's Baking Recipes.