Pour the chilled champagne into each flute, filling about two-thirds full, and set aside.
Gently add the cranberry juice to each glass, pouring slowly along the side to preserve the bubbles and create a vibrant, ruby hue.
If desired, stir in a splash of simple syrup to add a touch of sweetness, adjusting to your taste.
Drop a few fresh cranberries into each glass for a pop of color and tartness, letting them float on the surface.
Use a microplane or zester to create a twist of lemon zest, then gently place it on top of each drink for a citrusy aroma.
Gently stir the drink once to combine the flavors while keeping the bubbles lively.
Serve immediately, garnished with extra cranberries or lemon twists if desired, and enjoy the bright, tart sparkle of your cranberry mimosa.