Preheat the oven to 425 degrees. Place muffin liners in a muffin tin and set aside.
In a large mixing bowl, mash the bananas. Then mix in the eggs, milk, butter and vanilla. Add in the eggs and vanilla and mix until smooth. Add in heavy cream until well combined.
Slowly add in the flour, sugar, cocoa powder, baking powder, baking soda, and salt. Mix until just combined. Fill the muffin tins ¾ of the way with batter.
Bake for 6 minutes, then reduce the temperature to 350 for 9 minutes. Remove from the oven when a knife comes out of the center of a muffin clean.
Top with large sugar crystals. (optional)
Notes
Store in an airtight container in the refrigerator for up to 3 days or in the freezer for up to 2 months. Allow to come to room temperature before eating.