In a cocktail shaker, combine bitters, peach syrup, lime juice and mezcal.
Shake with ice, then fine strain into a coupe or flute.
Top with approximately 3 ounces of Prosecco.
Garnish with lime peel and serve.
Combine ingredients in a saucepan over medium to low heat and simmer for 15 minutes.
Cool with the peaches in it, then fine strain and store in the refrigerator to use as desired.