the day before: put the raspberries, lemon slices, 3 glasses of cane sugar syrup, kirsch and half lemonade in a large container and marinate in the fridge.
put the rest of lemonade and bottles of sparkling wine in the fridge.
just before serving:
added to the preparation the day before the rest of lemonade and bottles of crémant. taste and add sugar cane if necessary because certain sound more bitter than other crémants