Cut the melons in half, remove the seeds, scoop out the pulp with a baller and place them in the punch bowl. Tie a bunch of basil with a thread and place it on the melon balls. Pour the wine and leave the mixture to cool for at least 6 hours with the lid closed. Then remove the basil.
Roughly chop the remaining basil leaves.
Fill the punch with sparkling wine and sprinkle with basil leaves.