Preheat the oven to 350 degrees F and line a muffin tray with muffin cups (or lightly oil/spray the holes).
Add all of the ingredients except for the chocolate to a blender. Blend until well-combined and creamy. Fold in the chocolate chips (or chopped dark chocolate) into the batter until well-combined.
Fill the muffin holes 3/4 of the way up with muffin batter. Bake on the center rack of the preheated oven 18 to 20 minutes. Remove from oven and allow muffins to cool at least 30 minutes before unwrapping and eating (note: muffins will stick to the wrappers if you don't allow them to cool long enough ;)
Notes
*replace coffee grounds with 2 tsp instant coffee or instant espresso if you have either on hand**I chopped up an 85% dark chocolate bar rather than using chocolate chips