Baked pasta with Chicken sausage

1 T olive oil
1 medium red onion, chopped
4 cloves garlic
1 can (28 oz) crushed tomatoes with juice
1/2 t dried oregano
1/2 c heavy cream
1 pound rigatoni
10 oz baby spinach
12 oz smoked chicken sausage, sliced
6 oz fontina (or mozzarella) cheese
1/4 c grated parmesan cheese

Bring a large pot of salted water to a boil.  Heat oil in a large skillet over medium heat.  Add onion, cook until translucent, about 3 minutes.  Stir in garlic.  Cook for another minute.  Stir in tomatoes and oregano.  Cook until tomatoes are falling apart, 10-15 minutes. Add cream; cook until warmed through, about 5 minutes.  Season sauce with salt and pepper.
Preheat oven 10 400.  Cook pasta in boiling water.  Add spinach.  Drain, and return contents to pot.  Add tomato sauce, sausage, and cubed fontina to pot; toss to coat.  Season with salt and pepper.  Divide between two baking dishes.  Top with grated fontina and parmesan.  Bake for 20-30 minutes.