Chop the onion finely and slice the mushrooms. Sauté both in a bit of butter in a deep pan or pot until the mushrooms are lightly browned.
Cut the chicken into cubes/strips and add to the pan, let it brown.
Grate the zucchini coarsely and cut the cauliflower into small bite-sized pieces. Add both to the pan along with all other ingredients – except the pasta.
Let it all simmer for a few minutes.
Add the pasta and let it simmer until the pasta is tender. If the sauce is too thin, let it simmer a bit longer until it reduces more, and if it's too thick, add a little more water.
Season to taste and serve with a bit of grated Parmesan on top.