In a large pot, boil water and cook pasta to al dente according to package instructions. Drain, and set aside.While water is coming to a boil, begin next section. Remove casings from 5 links of Italian sausage.In a large pan, add 1 tbsp olive oil, and begin to warm over medium-high heat.Add Italian sausage to the pan, and cook over medium-high heat until there is no more pink showing (approx. 8-10 minutes). Break apart sausage into small pieces as it cooks.After the Italian sausage has finished cooking, remove from heat and drain excess fat from pan. Set aside. Remove stem, seeds, and ribs from bell pepper. Dice into ¼ inch pieces.Remove skin and ends from onion. Dice into ¼ inch pieces.Remove skin and ends from 3 cloves of garlic. Mince finely, or use a garlic press to mince.Wash and slice mushrooms. Set aside.
In a large pan, add 2 tbsp olive oil, and begin to warm over medium heat.
Add garlic, onion and bell pepper to the pan. Sauté vegetables over medium heat until the vegetables begin to soften (approx 4 min.)
Add sliced mushrooms, garlic salt, and Italian seasonings to the pan, and continue to sauté vegetables for an additional 5-6 minutes.
Add butter and flour to the pan. Incorporate into the vegetables for about 1 minute.
Add chicken stock. Stir.
Slowly add 2 cups heavy cream. Stir.
Add grated cheese. Stir.
Lower the temperature if needed. Continue cooking the sauce over a slow simmer (low-medium heat) for 10 minutes.
Remove from heat.
Add cooked sausage to the pan.
Add pasta to the pan.
The sauce will thicken as it cools.