Preparation
Add the chocolate wafers to a microwave-safe bowl and microwave in 30-second intervals, mixing between, until completely melted and smooth.
Pour the melted chocolate into the comet-shaped molds (to make 12 total; work in batches if needed), then refrigerate for about 5 minutes, or until the chocolate has set. Carefully remove the chocolate comets from the mold. Using a small brush, dust the chocolate figures with edible pearl dusting powder, if desired.
In a small bowl, mix together the silver and charcoal sanding sugar until evenly combined.
Add 2 cups of buttercream to a large piping bag fitted with a round tip, then pipe onto the red velvet cupcakes. Carefully dip the cupcakes in the sanding sugar mixture to cover the frosting completely.
In a small bowl, mix the remaining ⅓ cup of buttercream with the tangerine food coloring until evenly combined. Transfer the frosting to a piping bag fitted with a flat tip, then pipe onto the center of the cupcakes to look like a trailing flame. Sprinkle the flames with the gold sanding sugar.
Top each cupcake with a chocolate comet.
The cupcakes will keep, covered and chilled, for up to 3 days — bring them back to room temperature for about 20 minutes before serving so the buttercream softens.
