Insert a wood craft stick into the middle of each apple. Set aside on a piece of parchment paper.
Place heavy whipping cream, butter, sweetener, and salt in a shallow skillet over medium heat. Bring to a boil while stirring constantly. Reduce heat and simmer for 15-20 minutes or until thickened and darkens to medium brown color. The volume should be reduced, and mixture should coat the back of a spoon easily.
Removed from heat, stir in vanilla, and allow to cool slightly, about 3 minutes. Transfer caramel to a deep bowl.
Working quickly, dip each apple half of the way into the caramel (or entirely depending on preference), rolling to create a beautiful covering of caramel around the apple. Let any excess caramel drip off back into the bowl. Repeat for all of the apples. Set each back on the parchment and let Caramel Apples dry completely.
Enjoy immediately, or store in the refrigerator until ready to serve.
Note
If desired, sprinkle chopped peanuts on each immediately after rolling apple in the caramel. The best way to do this is to hold apple horizontally, and sprinkle peanuts as you twirl the apple around.