Place the gelatin in a small bowl and stir in the 8 tablespoons of champagne. Set aside. Spray an 8×8 pan with nonstick spray, then sprinkle some powdered sugar in the pan and shake well, dispersing it all over the pan, covering the entire thing.
In a small saucepan, combine the remaining champagne and sugar. Heat over medium heat, stirring constantly until the sugar is dissolved and bubbly, about 3 to 4 minutes. Stir in the gelatin mixture, whisking, and bring it to a boil. Once boiling, immediately remove from heat. Add to the bowl of an electric mixer attached with a whisk. Let sit and slightly cool. Add vanilla and salt. Beat on medium-high speed for 10 to 15 minutes, until white and glossy and shiny and thick. Spread in the 8×8 pan and top with a sprinkle of powdered sugar if desired. Let sit for about 4 hours, or even overnight.
Remove the marshmallows from the pan in one square and cut into pieces. You can cover the marshmallows with some of the sugar now, but it won’t fully stick until the chocolate is on.
Dip a corner of each into the melted chocolate and place on a piece of parchment to set. Let the chocolate cool and firm up slightly, but before it fully sets, cover it in a sprinkle of blood orange sugar! These last a few days if kept in a sealed container.