Optional: Wet the rim of two coupe glasses with a lemon wedge and dip in granulated sugar. Set aside.
To your Beast® Blender, add gin, cranberry juice, lemon juice, cranberry sauce (or syrup, if using), and crushed ice.
Blend until smooth and frosty.
Pour into two chilled coupe glasses, leaving a little space at the top.
Gently stir in Champagne or Prosecco to fill the glass. Stirring the bubbles ensures you won't lose the fizz.
Garnish with a melon twist or cranberries.