Bring a large pot of salted water to a boil. Add the penne pasta and cook according to package directions until al dente. Drain, reserving 1/2 cup of pasta water, and set aside.

While the pasta cooks, heat 2 tablespoons of olive oil in a large skillet or Dutch oven over medium-high heat. Add the sliced Andouille sausage and cook until browned and slightly crispy on both sides, about 5-7 minutes. Remove the sausage with a slotted spoon and set aside, leaving any rendered fat in the skillet.

Reduce heat to medium. Add 1 tablespoon of olive oil to the skillet (if needed, if enough sausage fat remains, you might not need extra). Add the diced yellow onion, green bell pepper, and red bell pepper. Sauté, stirring occasionally, until softened, about 5-7 minutes. Add the minced garlic and cook for another minute until fragrant.

Stir in the tomato paste, Cajun seasoning, dried oregano, and red pepper flakes (if using). Cook for 1-2 minutes, stirring constantly, to toast the spices and deepen their flavor.

Pour in the diced tomatoes (undrained) and chicken broth. Bring the mixture to a gentle simmer, then reduce heat to low and let it cook for 5-7 minutes, allowing the flavors to meld and the sauce to thicken slightly.

Stir in the heavy cream and grated Parmesan cheese until smooth and creamy. Return the cooked sausage to the skillet.

Add the drained cooked pasta to the skillet with the sauce and sausage. Toss everything together until the pasta is well coated. If the sauce is too thick, add a splash or two of the reserved pasta water until it reaches your desired consistency.

Taste and adjust seasoning with salt and black pepper as needed. Garnish with fresh chopped parsley and an extra sprinkle of Parmesan cheese before serving hot.