Peel zucchini, leaving half of green on.

Slice and add finely chopped onions.

Cover with salted water and cook until soft. DO NOT DRAIN LIQUID.

Mash zucchini and onions with potato masher and add milk, mushroom soup and butter. Beat all together, adding a little more liquid if desired until consistency you prefer.

Simmer on LOW, stirring often. Season to taste. The longer it stands, the better.