The key to this recipe is making sure the evaporated milk is very well chilled before whipping — put it in the refrigerator the night before, or even in the freezer for 30 minutes (do not let it freeze solid). The whipped evaporated milk is what gives this cheesecake its signature light, airy, almost mousse-like texture. Make sure the Jell-O has cooled completely before adding it to the cream cheese, or it may melt the whipped milk.