Preheat the oven & 10" cast iron skillet to 375°F.
Cream together the butter & sugars.
Mix in the eggs and vanilla.
Gradually mix in the flour, baking soda & salt.
I most frequently use Bob's Red Mill brand 1:1 gluten-free flour blend. You may need to adjust your flour measurement by 1-2 tbsp depending on the brand you use. The dough should have a traditional cookie dough thickness.
Fold in the chocolate chips.
Remove preheated skillet from the oven & grease with tallow or butter. Press the cookie dough flat into the pan.
Bake at 375°F for 20-25 minutes or until lightly golden brown on top but center is still jiggly (kind of like custard). It will continue to cook once removed from the oven.