Put all the ingredients into a blender except the chocolate chips (if using) and blend until well mixed. Stir in chocolate chips.
Pour batter into muffin pan. Drop a couple of chocolate chips onto the top of each muffin.
Bake 8-9 minutes. Muffins will puff up quite a bit but will level after cooling.
Notes
I used regular peanut butter (it has sugar in it) so I didn't add the honey. If you use natural peanut butter, I would add honey for sure. My pan was non-stick and made the sides of the muffins brown fast. So watch them and take out right when they are done. You can also make these in a regular sized muffin pan, just cook longer.
Recipe by Baked in AZ at http://bakedinaz.com/5-ingredient-blender-mini-muffins/