In a small saucepan over medium heat, melt ¼ cup unsalted butter. Once melted, stir in ⅓ cup light brown sugar. Whisk until the mixture begins to bubble.

Slowly add ½ cup heavy cream while whisking. Continue whisking for about 2-3 minutes until the sauce thickens enough to coat the back of a spoon.

Remove from heat and stir in ¼ teaspoon flaky sea salt. Allow to cool slightly.

In a medium bowl, whisk together 2 ¼ cups all-purpose flour, 2 tablespoons cornstarch, ½ teaspoon baking soda, and ¼ teaspoon fine sea salt until well combined.

In a large mixing bowl, beat ¾ cup softened unsalted butter with ¾ cup packed light brown sugar and ¼ cup granulated sugar until pale and fluffy.

Add 1 large egg and 1 teaspoon pure vanilla extract to the mixture. Mix on low speed until just incorporated.

Gradually add the dry ingredients, mixing on low speed until a cohesive dough forms. It may be slightly sticky.

Drizzle the warm caramel sauce over the dough and gently fold it into the dough with a spatula.

Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.

Drop portions of dough (about 2 tablespoons each) onto the prepared baking sheet, spaced 2 inches apart.

Bake for 12-14 minutes, until the edges are lightly golden and the centers remain soft.

Sprinkle flaky sea salt over each warm cookie as soon as they come out of the oven. Let them rest for 5 minutes before transferring to a wire rack to cool.