Bring a large pot of salted water to a boil and cook the fettuccine until al dente according to the package directions.Before draining, reserve 1 cup of the pasta water. Drain the pasta and set aside.
Heat a large skillet over medium-high heat.add the sliced beef sausage and cook until browned, about 5–7 minutes.Add the sliced green bell peppers and sauté until they're tender-crisp.Remove the sausage and peppers from the skillet and set aside
Using the same skillet, reduce the heat to medium.Add the butter, cream cheese, chicken stock, and half-and-half. Whisk until the cream cheese has completely melted and the sauce is smooth and creamy. add dry seasoning
Allow the sauce to simmer for 3 minutes.Stir in the shredded mozzarella cheese a handful at a time until it's fully melted and the sauce is smooth and cheesy.
Add the cooked fettuccine directly to the skillet and toss until every noodle is coated in the creamy sauce.Add a splash of the reserved pasta water as needed to loosen the sauce until it reaches your desired consistency.Fold in the cooked beef sausage and green bell peppers until everything is evenly combined.
Serve immediately and top each bowl with plenty of freshly grated Parmesan cheese.