Preheat oven to 350.

In a microwave safe mixing bowl melt the chopped chocolate, butter and coconut oil in 30 second increments, whisking until smooth.

Allow to cool for about 5 minutes.

Whisk in the brown sugar and coffee powder until smooth.

Whisk in the vanilla extract, peppermint extract, eggs and egg yolks until completely smooth.

Spoon the batter evenly into prepared jars and spread with the back of a spoon.

Place the jars on a baking sheet and place in the preheated oven.

Bake at 350 for 20-25 minutes.

Remove from oven and let cool completely before frosting.

Cream the butter until light and fluffy.

Add the powdered sugar and vanilla extract and mix until evenly distributed.

Add the milk, one tablespoon at a time, until the frosting gets to the desired consistency.

Top the cooled cakes with the frosting and peppermint bark if desired.