Pour .5 ounce of limoncello into a 7 ounce champagne flute.
Add .5 ounce of club soda or La Croix sparkling water to the glass.
Top off the cocktail with 6 ounces of prosecco.
Add a lemon twist and serve immediately.
Notes
Chill the limoncello for several hours before serving. High quality or homemade limoncello using 100 proof vodka can be frozen until ready to serve. Lower proof will be more like a slushy consistency but still delicious.
I could not find club soda so I chose to use the Limoncello flavored La Croix sparkling water. My drink was not sweet at all, which works for me. Club soda is traditionally used in Spritzer recipes.
A 750ml bottle of prosecco is equal to 25.36 ounces.