I'm not sure where I got this, but I've been using it for a few years
now and it works very well.
Homemade Cream Soup
2 1/4 c nonfat dry milk
3/4 c cornstarch
2 tb dried onion
1 ts basil
1 ts thyme
1/2 ts pepper
Combine all and store in an airtight container.
Sub for one can condensed soup: 1/3 c dry mix and 1 1/4 c cold water.
Cook and stir until thickened, or add to recipe.
Makes the equivalent of 9 cans of soup.
Note: the original recipe called for 1/4 c instant bouillon, I added 1/4 c
more dry milk instead. When a recipe calls for a cream of <whatever>, I
simply add fresh <whatever> along with the soup mix, or sub a veggie
more to our liking). Also, if you make the mix when you're going to use
a can's worth, the remainder will fit in a large Kraft parmesan cheese