Preheat oven to 350 degrees. In a medium bowl, whisk together flour, baking soda, and salt; set aside. In the bowl of an electric mixer fitted with the paddle attachment, cream butter and sugars until mixture is light and fluffy, about 2 minutes. Add egg and vanilla; mix until they are fully incorporated. Add flour mixture, and beat until just combined. Stir in chocolate chips.

Transfer dough to a 10-inch ovenproof skillet (I sprayed mine with just a little cooking spray), and press to flatten, covering bottom of pan. Bake until edges are brown and top is golden, 40 to 45 minutes. Don’t over-bake; it will continue to cook a few minutes out of the oven. Transfer to a wire rack to cool in pan, 15 to 20 minutes. Cut into wedges.