Heat a large skillet over medium-high heat. Add sausage links and cook until browned on the outside and mostly cooked through, about 8–10 minutes. Remove from the skillet and set aside to cool slightly. Slice into rounds once cooled.

Meanwhile, bring a large pot of salted water to a boil for the pasta.

Remove excess grease from the skillet, leaving about 1 tablespoon. Add the diced onion and cook until softened, about 4–5 minutes. Stir in the garlic and sliced roasted red pepper, and cook for another 2 minutes.

Add the butter to the skillet. Once melted, sprinkle in the flour and whisk to form a roux. Cook for 2 minutes, stirring constantly.

Stir in the chicken broth, salt, pepper, and red pepper flakes if using. Return the sliced sausage to the pan and stir in the heavy cream. Reduce heat to low and let simmer while the pasta cooks.

Add the fresh pasta to the boiling water and cook according to package directions, about 2 minutes. Reserve ½ cup of the pasta water.

Use tongs to transfer the cooked pasta directly into the sauce. Add the reserved pasta water and Parmesan cheese, then toss until evenly coated and creamy.

Garnish with chopped parsley and serve hot.