Place 2 cups of ice in a large pitcher. Slice the peaches and add the the pitcher along with the raspberries and the sugar. Add the white wine and leave in the fridge for about 2 hours.
Just before serving remove the pitcher from the fridge and add the champagne or prosecco and pour into wine glasses, making sure that each glass gets a peach wedge and some raspberries.
Garnish with mint leaves.