Preheat oven to 350 degrees. Grease a 10-inch cast iron skillet.
In a large bowl, microwave the chocolate and butter, stirring every 30 seconds until melted. Stir until well blended. Stir in sweetener and vanilla. Add eggs one at a time, stirring after each. Stir in almond flour a little at a time and mix until combined. Set aside.
In a small bowl, whisk the almond flour, baking soda, xanthan gum and salt.
In a large bowl, mix together the butter, sweenter, brown sugar substitute and vanilla. Add egg and stir until well combined. Add in almond flour mixture a little at a time, stirring after each addition. Fold the chocolate chips into the batter.
Spread brownie batter evenly in the skillet. Use a cookie scoop to drop cookie dough evenly across the top of brownie batter. Bake for 25-30 minutes. The edges of the cookies will be slightly brown, it's okay if they are still soft. It's great served warm but you can let it complely cool and slice it. It will firm up as it cools.