1 pink grapefruit
1 navel orange
1 cup Cointreau
1 750ml bottle Prosecco
12 to 24 ounces plain or grapefruit sparkling water
Slice the citrus fruit into half moons. Mix with the Cointreau in a pitcher that holds at least quarts. Add the Prosecco and cover the pitcher tightly with plastic wrap. Refrigerate overnight.
When ready to serve, top off the pitcher with sparkling water and serve with lime or orange wedges.