Heat 1 tablespoon of olive oil in a large deep skillet over medium heat. Add the sliced andouille sausage and cook for about 5–7 minutes, turning occasionally until browned on both sides.

Add the diced onion to the skillet with the sausage and sauté for 3–4 minutes until the onion becomes translucent and softened. Stir in minced garlic and cook for an additional 30 seconds until fragrant.

Stir in the uncooked penne pasta, chicken broth, heavy cream, diced tomatoes, Cajun seasoning, salt, and black pepper. Mix everything well.

Bring the mixture to a gentle simmer over medium heat. Cover loosely and cook for 12–15 minutes, stirring occasionally until the pasta is tender.

Remove from heat and fold in the grated Parmesan cheese until melted into the creamy sauce.

Sprinkle chopped fresh parsley over the top and serve warm.