Preheat oven to 350 degrees. Place cupcake holders in the cupcake pans, set aside.
Melt the butter with the semi-sweet baking chocolate. Cool slightly. Stir in cocoa.
Add the eggs to a mixer bowl and beat with a whisk for one minute. Add sugar, brown sugar and beat until thick and creamy, about 3 more minutes on medium high speed. Add vanilla.
Mix together the flour, baking powder, baking soda and salt.
Add half of the flour mixture and half of the buttermilk. When combined add remaining flour and buttermilk. Beat on medium high for 2 minutes.
Fill muffin cups ¾ full.
Bake for 18 minutes or until a tester pulls out clean. Cool.
Recipe by Recipes Food and Cooking at https://recipesfoodandcooking.com/2016/10/16/halloween-cupcakes/