Make the chantilly cream just before and store it in the fridge until ready to serve.
Place the heavy cream, mascarpone, icing sugar, and vanilla in a medium bowl. Using an electric beater on medium high in a circular motion, whip until thick. Place in an airtight container in the fridge.
240 grams cold heavy cream, 80 grams cold mascarpone, 60 grams powdered sugar, 2 tsp vanilla bean paste or pure vanilla extract
French Hot Chocolate
In a medium saucepan, stir together the milk, heavy cream, sugar, cinnamon, nutmeg, and espresso powder. Bring to a simmer over medium to medium low heat. Just enough to bubble slightly but not a boil.
480 grams whole milk, 120 grams heavy cream, 1 Tbsp dark brown sugar, 1/2 tsp espresso powder, 1/2 tsp ground cinnamon, 1/2 tsp ground nutmeg
Remove the pan from the heat, add the chopped chocolate and let it stand for a couple minutes to melt the chocolate. Whisk until smooth, then pour into warmed mugs.
285 grams dark chocolate 70% couverture
Top with a dollop of chantilly cream or marshmallows.