Place half of the sliced peaches into a ziplock bag. Freeze overnight.
When ready to make the bellinis, add peaches (frozen and fresh), blackberries and lemon juice to a blender. Blend until pureed.
Gather 6 to 8 champagne glasses. Add 1 to 2 Tbsp of the blackberry peach puree to each glass. Fill each glass with Martinelli’s Sparkling Cider.
Garnish with a blackberry and sprig of mint. Serve immediately.