Bring a large pot of salted water to a rolling boil. Add the penne pasta and cook until al dente according to package instructions.

Before draining, reserve about ¼ cup of pasta water. Drain the pasta and set aside.

Heat olive oil in a large skillet over medium heat. Add the chorizo and cook for about 5 to 7 minutes until browned and slightly crispy.

As the chorizo cooks, it will release flavorful oils that help build the sauce. Transfer the cooked chorizo to a plate, leaving the oils in the skillet.

Add the diced onion to the skillet and cook until softened, about 3 minutes. Stir in the garlic and red pepper flakes and cook for another minute until fragrant.

Add the crushed tomatoes, tomato paste, oregano, basil, salt, and black pepper. Stir well and allow the sauce to simmer gently for 10 minutes until slightly thickened.

Return the cooked chorizo to the skillet and stir it into the simmering Arrabiata sauce. Allow everything to cook together for about 3 to 4 minutes so the smoky flavors from the chorizo blend into the tomato sauce.

If the sauce becomes too thick, add a splash of the reserved pasta water to achieve a silky consistency.

Add the cooked pasta directly to the skillet and toss thoroughly until every piece is coated in the spicy tomato sauce.

Continue tossing for 1 to 2 minutes, adding a little reserved pasta water if needed. The starch in the pasta water helps the sauce cling beautifully to the pasta.

Remove from heat and divide the Chorizo Arrabiata among serving bowls.

Top with freshly chopped parsley, grated Parmesan cheese, and extra chili flakes if desired. Serve immediately while hot.