Chicken and Spinach Pasta Bake

This is one of our favorite recipes. The only downside is that it takes quite a while to prepare. But it's totally worth it, and to be honest, it's even better as a leftover.

Chicken and Spinach Pasta Bake
8 oz. uncooked rigatoni
1 TBS olive oil
1 cup chopped onion
1 (10 oz) pack frozen spinach, thawed
3 cups cubed, cooked chicken breasts
1 (14 oz) can Italian style diced tomatoes, drained
(I usually add half a can diced tomatoes as well and use the other half in spaghetti sauce later in the week. One can of tomatoes just doesn't seem enough)
1 (8 oz) container Philadelphia chive and onion cream cheese (softened)
1/2 tsp. salt
1/2 tsp. pepper
1 1/2 cup shredded mozzarella cheese

Prepare rigatoni according to package directions. Saute onions in olive oil until tender. Drain chopped spinach well, pressing between paper towels. Stir rigatoni, spinach, chicken and next 4 ingredients together with onions. Spoon mixture into dish and sprinkle evenly with shredded cheese. Bake covered at 375 for 30 minutes, uncover and bake 15 more minutes or until bubbly.