Pizookie

12 tablespoons unsalted butter ¾ cup packed (5 1/4 ounces) dark brown sugar ½ cup (3 1/2 ounces) granulated sugar 2 teaspoons vanilla extract 1 teaspoon salt 1 large egg plus 1 large yolk 1 ¾ cups (8 3/4 ounces) all-purpose flour ½ teaspoon baking soda 1 cup (6 ounces) semisweet chocolate chips Top with ice cream for an extra-decadent treat. 1. Adjust oven rack to upper-middle position and heat oven to 375 degrees. Melt 9 tablespoons butter in 12-inch cast-iron skillet over medium heat. Continue to cook, stirring constantly, until butter is dark golden brown, has nutty aroma, and bubbling subsides, about 5 minutes; transfer to large bowl. Stir remaining 3 tablespoons butter into hot butter until completely melted. 2. Whisk brown sugar, granulated sugar, vanilla, and salt into melted butter until smooth. Whisk in egg and yolk until smooth, about 30 seconds. Let mixture sit for 3 minutes, then whisk for 30 seconds. Repeat process of resting and whisking 2 more times until mixture is thick, smooth, and shiny. 3. Whisk flour and baking soda together in separate bowl, then stir flour mixture into butter mixture until just combined, about 1 minute. Stir in chocolate chips, making sure no flour pockets remain. 4. Wipe skillet clean with paper towels. Transfer dough to now-empty skillet and press into even layer with spatula. Transfer skillet to oven and bake until cookie is golden brown and edges are set, about 20 minutes, rotating skillet halfway through baking. Using potholders, transfer skillet to wire rack and let cookie cool for 30 minutes. Slice cookie into wedges and serve. Notes: made this for Andy's birthday "cake". My cast iron skillet is only 10 inches so I had to guess on the bake time and I think I ended up having it in for about 30 minutes. I thought it would have been better a little gooier but Andy liked how it soaked up milk. But we both agreed it needed more chocolate chips. Kate made again on 8/27/2021: we baked for 20 minutes and it was pretty perfect if not slightly underdone. We used 1.5 cups of chocolate super chips. Yummmmm