Prep the apples: Dice your apples into small, uniform cubes (about ¼ inch). You want them bite-size but not too tiny or they'll vanish into the dough.
Cook the apples: In a small frying pan over medium heat, combine the diced apples, 2 tbsp dark brown sugar, and cinnamon. Cook, stirring frequently, for about 5 minutes until the apples soften slightly but still hold their shape—they should be tender but not mushy. If you see liquid pooling at the bottom, you've gone too long. Transfer to a clean bowl and let cool completely while you make the dough.
Cream butter and sugars: In a large bowl, combine the softened butter, remaining ½ cup dark brown sugar, granulated sugar, and vanilla. Beat with an electric mixer on medium speed for 1-2 minutes until the mixture is pale and fluffy. Don't overbeat at this stage or the cookies may spread. Add the egg and beat until just combined.
Mix dry ingredients: In a medium bowl, whisk together the flour, baking soda, and salt. I like to whisk for at least 10 seconds to evenly distribute the soda and salt.
Combine: Add the dry ingredients to the butter mixture and fold gently with a spatula until mostly incorporated—a few streaks of flour are okay at this point.
Add the apples in two stages: Fold in half the cooled apples first, then add the remaining apples and fold just until evenly distributed. Important: Do not add any liquid that came out of the apples while they were cooling—pour it off before mixing. If the dough feels very soft or sticky, cover and refrigerate for 20 minutes.
Preheat and prepare sheets: Preheat your oven to 350°F. Line two large baking sheets with parchment paper.
Scoop the dough: Use a medium spring-loaded ice cream scoop (about 2 tablespoons) or two large spoons to scoop mounds of dough onto the prepared sheets, spacing them 2 inches apart. You should get 12-15 cookies total.
Bake: Bake one sheet at a time for 12-16 minutes. The cookies are done when the edges are browned and the bottoms are golden, and the tops are lightly golden but still soft in the center. For larger cookies (15 per batch), go closer to 16 minutes; for smaller ones (12-13), start checking at 12 minutes. Let cool on the baking sheet for exactly 2 minutes—this helps them set without breaking.
Transfer and finish: Move the cookies to a wire rack to cool completely. Once cool, drizzle with salted caramel sauce. I love to do a zigzag pattern for looks, but you can also just drizzle straight from a spoon. Serve at room temperature.