In a medium bowl, whisk together the flour, cornstarch, baking powder, baking soda and salt.
In a separate large bowl, beat together the butter, brown sugar and granulated sugar until creamed.
Mix the vanilla and egg into the butter mixture until you no longer see pieces of egg.
Carefully mix the dry ingredients into the butter mixture. I typically do about 1/2 at a time, starting with the mixer on a low speed and gradually increasing to a medium speed. Once all the dry ingredients are incorporated, turn off the mixer and squeeze the dough in your hand. If the dough sticks to your fingers, mix in 1 to 2 more tablespoons of flour.
Stir in 1/2 cup chocolate chips (reserve the other 1/4 cup for later).
Cover the bowl with plastic and chill in the fridge for about 30 minutes.
Remove the dough from the fridge. Scoop out about 1 to 1 1/2 tablespoons of dough and flatten slightly. Place one soft caramel in the middle of the dough. Then scoop out a second 1 to 1 1/2 tablespoons of dough and place on top of the caramel. Pinch the dough around the edges of the caramel so that it is entirely wrapped in cookie dough. Then roll into a ball.
Cover the cookie dough balls and freeze for at least 30 minutes. Alternatively, cookie dough balls can be placed in a freezer bag and frozen for up to 2 months.
When ready to bake, preheat the oven to 375F (190C) and line cookie sheets with parchment paper or silicone baking mats.
Place cookie dough balls about 2 inches (5 cm) apart on the lined cookie sheets.
Bake 1 cookie sheet at a time in the middle of the preheated oven. The cookies will bake for about 12-14 minutes, or until the tops look just set.
Remove the cookie tray from the oven. Optionally, place a few extra chocolate chips on the top of each cookie and sprinkle with a little extra sea salt.