In a large mixing bowl, beat together 1 cup melted unsalted butter, ¾ cup brown sugar and ¾ cup granulated sugar.
Mix until smooth and creamy.
Add 2 large eggs, one at a time, mixing well after each addition.
Stir in 1 Tbsp vanilla extract and mix until fully incorporated.
Add in 2½ cups all-purpose flour, 1 tsp salt and 1 tsp baking soda.
Beat for 2–3 minutes until a thick cookie dough forms.
Fold in 1½ cups milk chocolate chips by hand.
Transfer the cookie dough to a 10-inch cast iron skillet and spread it into an even layer.
Bake for 30–35 minutes, until the edges are golden brown and the center is still slightly soft and gooey.
Remove from the oven and allow the skillet cookie to rest for 10–15 minutes.
Scoop into serving portions and top with vanilla ice cream.
Serve warm.
Notes
Store leftovers at room temperature in an air tight container for up to 5 days.You can make the cookie dough ahead of time and press into the pan before baking. Make sure to keep the dough refrigerated until ready to bake.