2 T. unsalted butter
3-1/2 lbs. apples (such as Granny Smith and Honeycrisp; about 6 large apples), peeled and sliced 1/4" thick
3/4 c. sea salt caramel sauce, plus more for serving
3/4 c. packed light brown sugar
1 t. kosher salt
1 T. lemon juice
1/4 t. ground cinnamon
Pinch freshly grated nutmeg
6 T. cornstarch
2 t. pure vanilla extract
Melt butter in a large skillet over medium-high heat. Add apples and cook, stirring often, until crisp-tender, 10-12 minutes. Stir in caramel sauce, brown sugar, salt, lemon juice, cinnamon, nutmeg, and cornstarch. Cook, stirring often, until mixture come to a simmer and begins to thicken, 2-4 minutes. Remove from heat and stir in vanilla. Let cool.
Note: This filling was part of a recipe for slab pie, so it may make a lot of filling for a regular pie. But leftovers would be good.
Adapted from Country Living magazine, Nov. 2020, p. 89.