I like mushrooms but I find than champignons have very little taste. I guess that I grew up with wild mushrooms (and lots of porcini) so maybe I am a bit of a snob... still, champignons are easy to find and I tend to use them as a 'base', adding other dried mushrooms for extra flavour.
I had a handful of dried porcini and another of dried Chinese black mushrooms, and I soak them in water for 30 minutes. In the meantime I cleaned and chopped 400 g of champignons (I tend to discard the stalks of the champignons, not sure why, but I learned to do it ages ago in Italy and I keep doing it).
I heated some olive oil with a few cloves of garlic, then I added the champignons and some salt. I cooked the mushrooms until all their water was gone (abut 20 minutes) then I added the dried mushrooms and their soaking water.
After 5 minutes I added the content of a can of finely chopped Italian tomatoes, and some more water from rinsing the can (another 400 ml).
I let the mushrooms simmer, covered, for about one hour (yes that long) until almost all the liquid was gone. It may seem like a long cooking time, but it is winter after all, and it is nice to have a pot simmering on the stove :-).
At the end I added some fresh parsley chopped with a clove of garlic, (about one tbsp in all). I served it with crescentine (as one of the fillings, usually I always have one hot filling for them), but it works well on polenta or pasta, or as a side dish, or as a pie filler.