Set your eggs in a cup of warm (not hot) water to help them come up to room temperature. This will allow them to easily mix into the batter without solidifying the coconut oil.
Heat oven to 325 degrees.
Prepare your mini muffin pan by spraying with cooking spray or use a silicone non-stick pan.
In a medium bowl, combine butter, coconut oil, cocoa powder, sugar, and vanilla. Stir well to thoroughly combine.
Remove eggs from the water and break into the bowl. Stir in eggs and beat about 30 seconds to get them well integrated.
Stir in flour and mix just until combined. Add peppermint essential oil and stir.
Spoon the batter into the prepared baking cups. Be sure if you're using silicone that you place a baking sheet underneath it to keep it steady when you're moving it in and out of the oven.
Bake at 325 degrees for 8 - 11 minutes or until toothpick test shows a few moist crumbs. Do not overbake.
Remove from pans and allow to cool before enjoying with a bowl of ice cream or by themselves!