Preheat the oven to 350°F. Line or grease a muffin tray.
Whisk together in a medium bowl 2 cups of almond flour, 1/4 tsp of xanthan gum, 2 teaspoons of baking powder, and 1/4 tsp of salt. Set aside.
Beat 3 egg whites until soft peaks form and set aside.
Add 3 egg yolks and 1/2 a cup of monkfruit sweetener to a large bowl and beat with an electric mixer on medium speed until pale and fluffy, 2-3 minutes.
Incorporate 2 teaspoons of vanilla extract, 1/2 a tsp of rice or apple cider vinegar, and 1 cup of sour cream. Add flour mixture slowly until well incorporated.
Fold egg whites little by little very gently with a rubber spatula into the batter.
Add 1 cup of ChocZero milk chocolate chips and mix it gently. Spoon batter onto the prepared muffin tray.
Bake for 30 minutes or until lightly golden.
Allow to cool for 20 minutes in the pan before removing, and cool completely in a rack.
Notes
Make these keto muffins feel fresh even days after baking by placing them in the microwave for 15 seconds before eating.