Here's the soup I made last night, a variation on my standard recipe, using what I had on hand. This one turned out fantastic, the whole apartment smelled fantastic when we came home from football. This is what I used for this batch, but it's an enormously variable recipe.
1/2 white onion (yellow onions are fine, I just like the sweetness of the white onion)
10 chopped baby carrots (again, whole carrots would be fine, use 1 or 2, I just couldn't find the peeler)
2 stalks celery, chopped, with leaves (the leaves have the most flavour)
1/2 red pepper, chopped
1 small head of broccoli, chopped
1 russet potato, chopped (any potato is fine, russets are starchier and thicken soup nicely) 2 cups chicken broth (veggie broth is fine too)
1/2 tsp dried dill
1 tsp dried basil
I put the above ingredients in the crock pot on high for 4 hours (the time it took to get ready for football, attend the practice and get home, the timing worked out great.)
When we got home I added:
1 cup whole milk (give or take, I don't measure these kinds of things)
and then blended it all with the wand blender. If the soup seems too thick for you, add more milk, I added more at the table just to cool it off. After the milk, I added:
150grams old cheddar, grated (again, I didn't measure, I used about half the block, you can add more or less to taste) and
1 tsp salt
This soup will take just about any cheese nicely, and you can vary the flavour of the soup by varying the veggies and cheese you use. I like to add chopped, fresh spinach to this, in winter you could use cauliflower, cabbage, sweet potatoes, etc. Blue Cheese, Gouda, Swiss or any kind of smoked cheese is nice in this too. Potato, mushroom, onion, broccoli and swiss cheese is a really nice fall combo. Zucchini, tomato, spinach or other greens with mozzarela is a nice summer kind of dish. There are pretty well an infinite amount of variations, I just start with a base of onions, carrots, celery and potato in chicken broth, and add the dairy at the end to prevent curdling, everything else is variable.