To prepare the apples, thoroughly rinse the cold apples, and wipe well to remove the wax coating. Remove stem. Using a caramel apple stick, carefully push the stick into the apple, about 3/4 of the way. Place apples on a parchment-lined baking sheet with a baking rack.
To make the caramel, in a large heavy-bottomed saucepan over medium heat, combine the heavy cream, brown sugar, corn syrup, butter, and salt. Stir constantly with a wooden spoon until butter is melted.
Using a pastry brush dipped in water, brush the sides of the pan and place a candy thermometer into the mixture, ensuring it does not touch the bottom of the pan. Without stirring, allow the mixture to cook until mixture reaches 235 degrees, about 20 to 25 minutes. Remove from heat and gently stir in vanilla. Do not over-stir. Allow mixture to cool and thicken, about 10 to 15 minutes.
To dip the apples, working one apple at a time, hold the apple by the stick, dip the apple into the caramel mixture, and thoroughly coat using a twirling motion. If using toppings, roll the apple into the topping.
Set apple on prepared baking sheet with rack, ensuring the apples do not touch, Cool slightly and serve immediately, or allow to sit until caramel hardens, about 45 minutes. Enjoy day of for best results.