Step 1: Heat olive oil in a large, deep pot or Dutch oven over medium-high heat. Add the sliced sausage and cook until browned and slightly crispy, about 5-7 minutes. Remove the sausage with a slotted spoon and set aside, leaving rendered fat in the pot.
Step 2: Add the diced onion and bell pepper to the pot. Sauté for 5-7 minutes until softened. Add the minced garlic and Cajun seasoning, cook for 1 minute more until fragrant.
Step 3: Pour in the chicken broth and bring to a simmer, scraping any browned bits from the bottom of the pot. Add the dry pasta, stirring to ensure it's fully submerged in the liquid.
Step 4: Bring the mixture to a boil, then reduce heat to medium-low, cover, and simmer for 12-15 minutes, or until the pasta is al dente and most of the liquid has been absorbed. Stir occasionally to prevent sticking.
Step 5: Remove the pot from the heat. Stir in the heavy cream, fresh spinach, and shredded Parmesan cheese. Stir until the cheese is melted and the spinach has wilted.
Step 6: Return the cooked sausage to the pot. Toss everything together until well combined and coated in the creamy sauce. Taste and adjust seasoning with salt and pepper as needed.
Step 7: Serve immediately, garnished with extra Parmesan cheese and fresh parsley if desired.