Prepare your molds. If using paper cups, trim them down to about 2-3 inches in height. If using silicone molds, ensure they’re clean and completely dry.
Create a double boiler by placing a heatproof bowl over a pot with 1-2 inches of simmering water (not boiling). Make sure the water doesn’t touch the bottom of the bowl.
Melt the chocolate and coconut oil in the double boiler, stirring frequently until completely smooth. Alternatively, microwave in 30-second intervals, stirring between each until melted.
Let the melted chocolate cool slightly for 2-3 minutes. The chocolate should still be fluid but not hot enough to melt through paper cups.
Coat the inside of each mold by spooning about 2 tablespoons of melted chocolate into each cup and swirling it around to coat the sides. Use a clean pastry brush to ensure even coverage up to about ¼ inch from the top.
Place the coated cups on a baking sheet and refrigerate for 20 minutes until the first layer is set.
Apply a second coat of chocolate to reinforce the cups. This ensures they’ll be strong enough to hold hot liquid. Return to the refrigerator for another 30 minutes.
Carefully peel away the paper cups from the hardened chocolate, or if using silicone molds, gently pull the edges and pop out the chocolate cups. Work slowly to avoid breaking them.
Store the finished cups in the refrigerator until ready to use, placing them on a flat surface lined with parchment paper.
Prepare the hot chocolate by combining milk and cream in a medium saucepan over medium heat. Heat until it begins to steam but doesn’t boil.
Add chopped chocolate, sugar, vanilla, and salt to the hot milk mixture, whisking continuously until the chocolate is melted and the mixture is smooth.
Remove from heat and stir in liqueur if using. Keep warm until ready to serve.
Set up a serving station with the chocolate cups, hot chocolate in a pouring vessel, and all garnishes in separate bowls.
To serve, carefully pour the hot chocolate into each chocolate cup, leaving about ½ inch of space at the top for garnishes.
Top with whipped cream and festive garnishes of your choice, such as crushed candy canes, sprinkles, or marshmallows.
Serve immediately on saucers with spoons, instructing guests to enjoy the drink and eat the cup as it softens.