Layer chopped cabbage in a 13 x 11 pan. Layer jar alfredo sauce on top. Add salt and pepper to taste. Add shredded parmeson cheese on top.
Slice your sausage into 1/2-inch pieces. Heat pan with 1 tsp of olive oil and add sausage. Let brown on both sides and add chopped onion. When onions are soft add garlic and heat for just a couple of minutes. Take off the heat and then layer on top of cabbage mixture.
Add another layer of shredded parmesan cheese on top of cabbage mixture.
Cover with foil and bake for 30 minutes. If you like for the cheese to be a bit brown, take off foil and broil just for a few minutes.