Cream of mushroom is generally pretty mediocre from a can, but it's a good base to make a great soup from.
In a large pot, saute 1 medium onion, sliced thinly, with a variety of mushrooms (I use portobello and white) sliced thin. When the onions are translucent, turn the heat down and add the condensed soup + 1 can of water or milk. Whisk the onions, mushrooms and soup until fully blended. Add 1/2 package frozen cauliflower and 1/2 package frozen broccoli. Keep heat at medium, cover until soup is bubbling. When soup is bubbling gently, season with salt and pepper to taste. Remove from heat and serve, garnishing with cheddar if desired.