1/3 cup fresh ricotta (not the packaged kind, it’s really not the same.)
1/4 cup grated parmigiano (or cheese of your choice)
Heat a skillet over medium heat, add the oil and the chili flakes. Let sizzle for a few seconds. Add the chopped onion and the zucchini and season with salt and pepper.
Cover and cook, stirring occasionally, until the zucchini are tender. In the meantime, bring a pot of salted water to a boil, and cook the penne according to instructions for al dente. Drain, reserving about 1/3 cup of the pasta cooking liquid. (You probably won’t use it all.)
Toss penne in the skillet with the zucchini, lowering the heat to a simmer. Add the ricotta and a bit of the water at a time, until desired consistency is reached. Sprinkle with the parmigiano and serve immediately.