Step 1In a blender, puree the peeled, seeded peach. Set aside.
Step 2In a pint glass, hand press 2 thyme sprigs with a muddler. Add 1 ounce of the peach puree, the simple syrup, the Prosecco and the bitters.
Step 3Fill the glass with ice. Stir swiftly for 30 seconds.
Step 4Strain into a flute. Garnish with the remaining thyme sprig.