*For homemade syrup: Mix 1 cup water, 1/2 cup honey, 1/2 cup white sugar, and 3 rosemary sprigs. Dissolve sugar in water over medium heat once dissolved reduce heat to low add rosemary allow to simmer on low heat for 15-20 min remove from heat allow to sit for another 15-20 min. Strain to remove rosemary leaves.
Combine gin, simple syrup, lemon juice, and egg white in shaker with ice shake vigorously then shake even more vigorously. Strain into glass and top with prosecco. Add a fresh rosemary sprig for garnish.