Slice the smoked sausage into thin rounds. Dice the bell peppers and onion. Measure out the Cajun seasoning, heavy cream, and Parmesan cheese before you begin cooking.

Heat olive oil in a large skillet or pot over medium-high heat. Add the sausage and cook for 3 to 4 minutes until browned on both sides. Remove and set aside, leaving the drippings in the pot.

In the same pot, cook the bell peppers and onion over medium heat for about 3 minutes until softened. Add Cajun seasoning and stir for 30 seconds to toast the spices.

Pour in the chicken broth and bring to a gentle simmer. Add the dry pasta directly to the pot and stir. Cook uncovered for 10 to 12 minutes, stirring occasionally, until pasta is al dente and most of the broth is absorbed. If the pasta looks dry before it is cooked through, add a splash more broth.

Reduce heat to low. Stir in the heavy cream and Parmesan until the sauce is smooth and creamy. Return the sausage to the pot and stir to combine. Add fresh spinach if using and stir until wilted, about 1 minute.

Taste before adding salt. Adjust with black pepper or cayenne as preferred. Garnish with chopped parsley and serve immediately.