My best friend made this the other day and I just had to have the recipe. It's filling and soooo good! The recipe can easily be halved. This recipe comes from a German cookbook and a German packet of leek soup is enough for 3 cups of water. As far as I can tell from looking on the internet that's the same for Knorr leek soup in the US. If I am wrong please use enough of the soup mix to make 9 cups. If you add the optional ingredients you might want to reduce the amount of whole kernel corn, otherwise the soup becomes really thick. Where I live you can buy cans of whole kernel corn that have some kidney beans added, those work really well. Can easily be prepared ahead and reheated.