Thoroughly clean and dry each apple. Remove stems and place twigs or sticks into tops of apples. Set aside on a parchment-lined baking sheet.
In a small saucepan, heat butter over medium-low heat, swirling occasionally. Use a spatula to scrape butter from the bottom and sides so it heats evenly.
Cook until small brown specks appear and butter smells nutty. Remove from heat and allow to cool while you heat the sugar.
Place sugar and corn syrup into a medium pot fitted with a candy thermometer over medium-low heat. Use a wooden spoon to stir the sugar and corn syrup together.
Once the sugar dissolves and begins to boil, stop stirring with the spoon. Resist the urge to stir from now on– doing so may cause your sugar to crystallize. You should, however, swirl the pot every minute or so.
Heat sugar mixture until it reaches 300°F. The sugar should be a light/medium brown color- any darker and it will taste burned! Immediately remove from heat.
Stir in brown butter, then stir in heavy cream, bourbon, and salt, stirring constantly while your mixture bubbles away.
Place mixture back on medium-low heat and heat until it reaches 240°F. Immediately remove from heat.
One by one, dip apples into the caramel, twirling around to coat evenly. Lightly shake apple over caramel so excess drips off. Place onto parchment-lined baking sheet. Repeat. Should your apples begin to get bubbles on them, place caramel back onto the stove over a low heat.