Preheat oven to 350 degree F. Prepare cupcake tin with cupcake liners. Set aside.
In a large mixing bowl, add chopped chocolate and cocoa powder. Pour hot coffee over both, then stir until chocolate is melted.
Add sugar, flour, kosher salt, baking soda and baking powder. Add in vanilla extract, eggs, vegetable oil, and buttermilk. Beat for about 4 minutes, scraping down the sides of the mixing bowl several times (and the bottom too to make sure the chocolate doesn't settle).
The batter will be thin, that's okay! Using a large cookie scoop, spoon batter into prepared cupcake tins, about ⅔ full. Bake for 18-20 minutes, until a toothpick in the center comes out clean, or the cupcake springs back from a touch of your finger.
Remove and cool completely on wire rack.
For the Frosting
In a large mixing bowl, using an electric mixer, beat butter for 3-4 minutes. Do this until the butter becomes pale in color.
Add in milk, sugar, peppermint and food coloring. Beat an additional 3-5 minutes until frosting is light and fluffy (add more milk if needed).
Fold in chocolate chips.
Notes
Use hot coffee. The warmth of the coffee helps melt the chocolate, making it easier to incorporate info the batter. If you use leftover brewed coffee, reheat it in the microwave for 1 minute before adding to the cocoa.
Scrape the bowl: As you mix the dry ingredients into the wet, scrape down the sides and bottom of the bowl to ensure the chocolate doesn't settle.
Use good quality chocolate. The better the cocoa and chocolate squares you use, the better the finished cupcakes will taste.
How to tell when cupcakes are done. Some people swear by the toothpick test. I prefer to touch the tops of the cupcakes. If it bounces right back, the cupcakes are done. If it stays indented, they need a little longer.
STORAGE: Store cupcakes at room temperature in covered container for up to 4 days. Or freeze for up to 3 months.