Bring a large pot of heavily salted water to a boil. Cook the penne according to package directions until al dente. Drain and set aside.

While the pasta water heats, place a large deep skillet over medium-high heat and add the olive oil. Add the sausage, breaking it apart with a wooden spoon as it cooks. Brown the sausage for about 5 to 6 minutes until it is cooked through with some browned bits in the pan. Transfer to a plate and leave the drippings in the skillet.

Add the diced onion to the skillet and cook over medium heat for about 3 minutes, stirring occasionally, until softened and starting to turn translucent. Add the garlic and cook for another 60 seconds until fragrant.

Add the diced zucchini and stir everything together. Cook for about 3 to 4 minutes, letting the zucchini pick up a little color on the edges. Season with the Italian seasoning, salt, and black pepper.

Pour in the crushed tomatoes and stir to combine, scraping up any browned bits from the bottom of the pan. Return the browned sausage to the skillet. Reduce the heat to medium-low and let the sauce simmer for about 8 minutes, stirring occasionally, until it thickens slightly and the flavors come together.

Add the drained penne to the skillet and toss everything together until the pasta is coated in the sauce. Taste and adjust salt. Serve in bowls or straight from the skillet with a generous shower of Pecorino Romano on top.