In a large skillet or pot large enough to hold the entire pasta dish, simmer the sausage links in water enough to cover them. Medium high heat, about 15 minutes until cooked through.
Meanwhile, set a separate pot of water to boil. Add a pinch of salt and cook the pasta al dente, about 11 to 12 minutes. Reserve about 1 cup of the starchy pasta cooking water BEFORE DRAINING. Use a measuring cup or coffee mug to pull some out. This can be used if needed to adjust the consistency of the sauce.
Prep your vegetables while the sausage simmers. Chop onions and slice bell pepper, then cut the slices in half. Mince the garlic.
Remove the sausage links from the pan and discard the water. Rinse out the pan but no need to wash. Return the pot over medium heat and add the olive oil. Brown the sausage in the pot, about 5 minutes.
Add the onions and peppers to saute along with the sausage, seasoning them with salt, pepper and Italian seasoning. When the sausage links are browned, remove them to a cutting board. Cut them in slices and return them to the sautéing onions and peppers. About 10 minutes.
When the veggies are softened and beginning to caramelize, add the garlic and cook another minute until fragrant.
Add the tomato sauce, half & half, and spinach and simmer about 5 minutes over medium to medium low heat until the spinach is wilted in.
Add the pasta and mix well with the sauce. If your sauce becomes too thick at any point, add a bit of the starchy pasta water to get it back to the right consistency. It will continue to thicken the longer it sits on the burner. Serve with fresh Italian herbs and shaved Parmesan cheese (use a vegetable peeler).