Preheat the oven to 350°F. Line baking sheet with parchment paper.
Whisk together the flour, cornstarch, baking soda, and salt in a large bowl.
In the bowl of a stand mixer fitted with a paddle attachment, cream together the butter, sugar, and brown sugar on medium speed until creamy, about 2 minutes. Add the egg and vanilla and mix until smooth.
Gradually add the flour mixture into the wet ingredients and mix on low speed just until combined. Stir in chocolate chips.
Using a large cookie scoop (or about 2 Tablespoons), spoon dough into hand and roll into a ball. Slightly flatten the the ball with the palm of your hand. Place a piece of caramel in the center of the dough and wrap the cookie dough around the caramel. Make sure the caramel is completely covered by dough. Place on prepared cookie sheet about 2 inches apart.
Bake the cookies for 10-12 minutes, until slightly browned around the edges.
Remove from oven and sprinkle with flaky sea salt. Let set on the pan 5 minutes before transferring to a wire rack to cool completely.
Notes
Caramels: Use soft caramels like Werther's Soft Caramels or Trader Joe's Fleur de Sel Caramels.To store: Keep cookies in an airtight container at room temperature for up to 3 days.To freeze baked cookies: Freeze in an airtight container for up to 3 months. Thaw at room temperature before serving.To freeze cookie dough: Scoop and stuff the dough balls with caramel, then flash freeze on a baking sheet until solid. Transfer to a freezer bag and freeze for up to 3 months. Bake straight from frozen, adding an extra minute or two to the bake time.Adapted from Let's Eat Cookies by Maria Lichtyfor my Cookbook Fanatics Series.