Bring a large pot of salted water to a boil and add pasta. Cook according to package instructions until al dente. Drain from water and set aside.
Add sausage slices to a large saute pan and sear over medium-high heat until well browned on both sides.
Remove sausage from the saute pan and add red pepper and onion. Saute these in the rendered sausage fat (you can add cooking oil if needed). Once almost tender, add garlic and cook for an additional minute.
Remove peppers, onion, and garlic and set aside with the sausage.
Add chicken broth and scrape the bottom of the pan to loosen any burnt on fond, then add heavy cream, Cajun seasonings, and stir to combine.
Bring liquid to a simmer then reduce the heat to medium-low and continue to simmer for 10 minutes, or until thickened. Stir in one tablespoon of flour to thicken it further.
Remove saute pan from heat and slowly sprinkle in the Parmesan cheese in batches, while stirring it into the sauce, then add the fire roasted tomatoes.
Add pasta, sausage, peppers, onion, and garlic to the sauce and toss to combine.
Serve immediately.
Notes
Optional: Top with green onions for a pop of color.