Preheat your oven to 350°F (175°C) and line a cupcake tin with paper liners. In a large bowl, sift together the flour, cocoa powder, baking soda, salt, and sugar. In a separate bowl, whisk together the buttermilk, vanilla extract, eggs, sour cream, and optional melted butter until combined.

Gradually add the dry mixture to the wet ingredients with the mixer running on low speed. Mix until just combined, being careful not to overmix.

Scoop approximately three tablespoons of batter into each cupcake liner. Bake for 15-20 minutes, or until a toothpick inserted in the center comes out clean. Allow cupcakes to cool completely before frosting.

Cream the unsalted butter until light and fluffy. Gradually add the confectioners' sugar and beat on high speed. Add milk or cream one tablespoon at a time until you achieve the desired frosting consistency. Divide the frosting in half; mix green food coloring into one half.

Cover each cupcake with the white frosting, texturing it slightly to resemble snow. Apply a thin layer of green buttercream to the sugar cones for better coverage. Optionally, fill the cones with candy.

Using a piping bag fitted with a #30 star tip, pipe star-shaped dollops of green frosting onto the sugar cone, starting from the bottom and working upwards to form the tree shape.

Dust the cupcakes with additional confectioners' sugar to mimic snow on the trees. Serve and enjoy.