Start by cooking the pasta. Whatever the amount of time the package suggests, shorten it by 2 or 3 minutes. Before draining, save one cup of the pasta water.

In a large skillet, over medium heat, cook the onions in the olive oil until just cooked through, about 3-5 minutes.

Add in the dried red chili flakes, if using, and the garlic. Stir to combine and cook for 2 more minutes.

Once the garlic is cooked, stir in the tomato paste and pasta water to combine it with the onions and garlic.

Add all of the tomatoes, along with the salt and ground black pepper.

Cook the tomatoes whole until they slightly blister and you can burst a few with a wooden spoon, about 8-10 minutes.

Now, add the zucchini and stir to combine with the other ingredients. Cook for 2-3 minutes.

Add the cooked pasta and stir into the sauce. Cook for another 2-3 minutes, until the pasta is fully re-heated.

Remove from heat and stir in the parmesan cheese. Plate, garnish, and serve immediately.