Step 1

Preheat oven to 350°F. Spray 1–6 5-inch cast iron skillets (depending on how many cookies you want to bake) with nonstick spray and place on a baking sheet.

Step 2

Add the softened butter, brown sugar, and granulated sugar to a large mixing bowl and stir until combined.

Step 3

Add the egg and vanilla to the butter mixture and stir again until combined.

Step 4

Add the flour, baking soda, and kosher salt to a separate mixing bowl and whisk together.

Step 5

Add the dry ingredients to the wet ingredients and stir until just incorporated.

Step 6

Add the chocolate and stir until distributed throughout the dough.

Step 7

Divide the dough into six portions, approximately 1/4 cup each.

Step 8

Add one dough portion to each skillet (freeze any you are not baking right now for later). Sprinkle the top of the dough with flaky sea salt.

Step 9

Bake until the edges look wrinkly and the top is a deep golden brown, about 15-17 minutes. Let cool for about 10 minutes before serving, preferably with a scoop of vanilla ice cream.