Baked Ziti with Sausage and Peppers

1 Tbsp olive oil
1 lb Italian sausage, removed from its casing
2 onions, minced
1 green bell pepper, stemmed, seeded, and cut into 1/2 inch pieces
1 red bell pepper, stemmed, seeded, and cut into 1/2 inch pieces
4 garlic cloves, minced
1 Tbsp minced fresh oregano or 1 tsp dried
1 28-oz can crushed tomatoes
1/2 cup heavy cream
8 oz ziti
1/2 tsp salt
1/4 tsp peper
1 15-oz can tomato sauce
hot water, as needed
1 cup shredded mozzarella (4 oz)

Line slow cooker with aluminum foil color and coat with vegetable oil spray.  Heat oil in large pot over medium high heat until just smoking.  Brown sausage well, breaking up large pieces with wooden spoon, about 5 minutes.  Add onions, bell peppers, garlic, and oregano and cook 8-10 minutes. stir in tomatoes and heavy cream, scraping up any browned bits, and simmer until thickened slightly, about 5 minutes.  Stir in ziti, salt and peper.  Transfer ziti mixture to prepared sow cooker and spread tomato sauce evenly over pasta.  Cover and cook 3 hours on high. Remove foil colar.  Gently stir pasta, adding hot water as needed to loosen sauce consistency.  Sprinkle with mozzarella, cover and let sit until melted, about 5 minutes.