Preheat oven to 350°F. Line baking sheets with parchment paper.
Whisk flour, cornstarch, baking soda, and sea salt in a bowl.
Beat butter and both sugars until fluffy (2 minutes).
Add egg and vanilla; beat until combined.
Mix in dry ingredients gradually.
Stir in chocolate chips.
Scoop 2 tablespoons dough, flatten, add caramel in center.
Wrap dough around caramel, seal completely.
Place cookies 2 inches apart on baking sheet.
Bake 10-12 minutes until edges are golden.
Sprinkle hot cookies with sea salt.
Cool 5 minutes on sheet, then transfer to rack.