Preheat the oven and line a muffin pan with cupcake liners. The pan should be ready before the batter goes in.
Fill each liner about two-thirds full with chocolate cupcake batter. The batter should look smooth and thick.
Bake until the tops look set and a toothpick comes out mostly clean. The cupcakes should spring back when lightly pressed.
Let the cupcakes cool fully on a rack. They should feel cool to the touch before frosting.
Pipe or spread the peppermint frosting on top in a swirl. The frosting should hold its shape.
Drizzle chocolate sauce over the frosting. Let it fall naturally down the sides.
Sprinkle crushed peppermint candy on top. Add a peppermint stick if using.