Heat milk in a thick-bottomed vessel and bring to a boil. Reduce heat and simmer for eight to ten minutes. Add sugar and continue to simmer for another ten minutes or till slightly thick and creamy. Remove from heat.
When cool. Stir in the kewra water and put to chill in the refrigerator. Combine the melons scoops and divide equally amongst four tall glasses, pour chilled milk over, garnish with pistachio and serve.