In a large pot over medium-high heat, add oil. Once hot, add sausage and cook for about 3-5 minutes on each side, or until brown.
Transfer to a plate and tent to keep warm. To the same pan add onions and cook until softened (about 5-8 minutes).
Add garlic. Cook for one more minute, or until fragrant.
Add tomatoes, broth, cream, salt, pepper, red pepper flakes, dry pasta noodles, and cooked sausage, stir to combine. Press noodles down slightly so they are fully covered with the liquid.
Reduce heat to medium. Cover and simmer for 15-20 minutes, or until pasta is cooked al dente. Stir occasionally. (Please note: Cooking times may vary, depending on the type of noodle you used.)
Remove pot from heat. Add cheeses and stir together until cheeses are melted. Let rest, uncovered, for 5-10 minutes to allow the sauce to thicken.
Garnish with parsley and serve hot.
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Notes
***This recipe has been updated based on reader feedback.