Start by bringing a large pot of salted water to a boil. Add the penne pasta and cook according to the package instructions until al dente—usually around 10-12 minutes. Once done, drain the pasta and set aside, reserving about ½ cup of the pasta water for later use.
While the pasta cooks, heat the olive oil in a large skillet over medium heat. Add the diced onion and sauté until translucent and soft, about 5 minutes. Toss in the minced garlic and cook for an additional 1-2 minutes until fragrant but not browned.
Add the chicken chorizo to the skillet, breaking it into smaller pieces as it cooks. Let it brown evenly, stirring occasionally, until fully cooked through and slightly crispy on the edges. This step is key because the flavorful fat released will enrich the sauce.
Pour in the canned diced tomatoes along with their juices. Stir in the red pepper flakes and dried oregano. Season with salt and pepper to taste. Let the sauce simmer gently for 10 minutes, allowing the flavors to meld and the sauce to thicken slightly.
Add the cooked penne pasta to the skillet, tossing well to coat every bite in the spicy tomato sauce. If the sauce feels too thick, splash in some of the reserved pasta water to loosen it up and create a silky finish.
Remove from heat and sprinkle fresh basil leaves over the top. Serve immediately with a generous grating of Parmesan cheese if desired. This dish pairs beautifully with a crisp green salad or some crusty bread for mopping up extra sauce.