To a large pan, add the oil to coat the bottom over medium heat. Add the sausage and break it up as it cooks with a wooden spoon. Cook until browned and almost cooked throughout, about 5 minutes. Just before the sausage is finished cooking, drain off the excess fat rendered from the sausage, leaving behind about a tablespoon.
1 Tbsp vegetable oil, 1 Lb. mild Italian sausage
Next, add the chopped onions to the browned sausage and cook until the onions are translucent, about 5-7 minutes.
¼ cup onion
Add the rosemary, fennel seeds, cloves, and cream to the sausage and onions and stir. Turn the heat off and set aside.
1 Tbsp fresh rosemary, 2 tsp fennel seeds, ½ tsp ground cloves, 1 cup heavy cream
In a separate large skillet, melt the butter over medium to medium-high heat until it stops foaming. Add the mushrooms and cook, stirring often, until the mushrooms are tender and have begun to brown, about 5-7 minutes. Add the garlic, pepper, and salt, stir and cook for about 30 seconds. Pour in the vermouth and wine to deglaze and cook until most of the liquid has evaporated, about 3-4 minutes.
1 Tbsp unsalted butter, 12 oz cremini mushrooms, 4 cloves garlic, ½ tsp black pepper, 1 tsp kosher salt, ¼ cup sweet vermouth, ¼ cup dry white wine
Add the mushroom mixture to the sausage and cream mixture and stir. Stir in the lemon juice and parsley. Keep this mixture simmering on low while you cook the pasta.
2 Tbsp lemon juice, 2 Tbsp fresh parsley