This is my current favorite soup.  I like that my kids can make it for me with a bit of instruction and I can do as little as necessary.

Potato Leek Soup

1 Leek
2 Onions
bit o' butter

1 box Vegetable Broth

Salt & Pepper
1/2 tsp Thyme

1 cup buttermilk  (make this using one cup milk with 1 tbsp. white vinegar.)
Instant mashed potatoes or dehydrated potato flakes.

Slice the leeks and onions, saute in a pan with butter till soft.  Pour in your vegetable broth, some salt and pepper, and the thyme. Shove in that buttermilk too. Enter the stick blender if you have one, whhizzz until everything is creamed.  If you don't have one, no worries, you have a chunky soup. 
Now add a few sprinkles of the potatoes.  Keep adding until it's a consistency you like.... if you go overboard add a bit of milk or water. 

Yummo, soup in 15 min.

Now in case you think I'm the only one cheating like this... check this out...
http://www.goodhousekeeping.com/recipefinder/potato-leek-soup