Preheat oven to 325F and line 9 muffin cups with paper liners (I recommend parchment paper liners for easy release).
In the bottom of a good strong blender (I recommend Blendtec or Vitamix), add eggs, almond milk or water and vanilla extract. Blend briefly to combine.
Add almond flour, coconut flour, cocoa powder, sweetener, baking powder and salt. Blend on medium high until smooth (you may need to scrape down sides of blender a little to make sure everything combines). Add melted coconut oil and blend until combined.
Stir in all but 1 tablespoon of chocolate chips. Divide batter evenly among prepared muffin cups and top each with a few more chocolate chips.
Bake 22 to 25 minutes, until firm to the touch. Remove and let cool in pan.
Notes
This updated recipe uses a liquid oil, like avocado oil, in place of the melted coconut oil. The coconut oil is delicious but it thickens the batter considerably, making it harder to get out of the blender.