Add 1/4 cup buttermilk and 2 Tbsp chocolate chips into a heatproof bowl. Heat in the microwave for 15-30 seconds or over a double boiler until the chocolate has melted.

Whisk together until the ingredients have combined, making sure all the chocolate is melted.

Add 1/4 cup all-purpose flour, 1/4 cup granulated sugar, 2 Tbsp cocoa powder, 1/4 tsp baking soda and 1/4 tsp salt into chocolate mixture and stir until combined.

Add 1 large egg, 2 Tbsp vegetable oil, 1/4 tsp vinegar and 1/4 tsp vanilla. Mix just until the batter is smooth.

Fill the mini cupcake liners 3/4 full and bake for about 9-10 minutes or until a toothpick comes out with a few moist crumbs. If you have leftover batter, let it sit at room temp and bake a second batch once the first has baked.

Let the cupcakes cool for 5 minutes in the pan before moving them to a cooling rack to finish cooling.

Mix 1/4 cup of salted butter and 1/2 tsp vanilla extract together into a medium sized bowl.

Slowly stir in 1/2 cup powdered sugar, 1/4 cup cocoa powder, and 2 Tbsp of heavy cream or milk.

Pour in 1/4 cup of melted and cooled chocolate into the buttercream and mix until combined.

If the frosting seems too thick, add an extra tsp of heavy cream. If it's too thin, add in another Tbsp of powdered sugar.