Preheat oven to 350°F.
In a medium bowl, whisk egg to beat.
Add in maple, butter, vanilla, and milk and whisk. Add brown sugar and whisk.
Stir in peanut butter to combine.
In another bowl, combine, almond flour, baking soda, and sea salt and stir.
Add dry ingredients to wet ingredients and stir to combine.
Pour dough into an 8" cast iron skillet coated with desired oil to season.
Sprinkle extra sea salt over the dough.
Bake for about 18-20 minutes or until edges begin to brown and cookie is cooked through. (I like mine to be a bit gooey still so I can eat it with a spoon, 18 minutes please!)
Allow to cool for about 10-15 minutes before eating. (Ha, like that is gonna happen...)