How to Make It
Place fresh cherries in a glass container or jar; pour amaretto over cherries. Cover, shake gently, and let stand in a cool, dry place for at least 48 hours or up to 2 weeks.
Strain the cherries through a fine sieve over a bowl, reserving amaretto and cherries.
Pour amaretto into a large cocktail shaker or quart-sized mason jar. Add lemon juice and egg whites. Add as much ice as possible, cover, and shake vigorously for 15 seconds. Strain about 1/4 cup into each of 8 chilled cocktail coupes or Champagne flutes; top each serving with 1/4 cup prosecco. Garnish with amaretto-soaked cherries, if desired. Serve immediately.