Three Cheese Chicken Penne Pasta

This is my mother-in-law's recipe and it's so yummy.

Ingredients:

2 cups (8 oz) multigrain penne pasta, uncooked (I just had regular pasta, so I used that instead. Also, I might use 2 1/2 cups next time.)
1 pkg (9 oz) fresh spinach leaves (I didn't use that much, but next time I will use more)
1 T oil
1 - 1 1/2 lb boneless, skinless chicken breasts, cut into bite-size pieces (I used one breast and it was plenty)
1 onion, cut in half and sliced thin
1 T minced garlic
1 tsp dried basil leaves
1 jar spaghetti sauce
1 can diced tomatoes, drained (I didn't use them this time because the sauce already had tomatoes in it and Derek doesn't really like them)
4 oz (1/2 pkg) cream cheese, cubed
2 cups mozzarella cheese, divided (I used whatever cheese I had)
1/2-1/3 cup grated Parmesan cheese

Heat oven to 375 degrees.

Cook pasta until al dente. Add spinach to boiling water with pasta (after it is done) for abou 30 seconds. Drain pasta mixture and return to pan (you'll want a good-sized pan).

Heat 1 T oil in another pan, stir in chicken, onion, garlic and basil on medium-high heat for 3 minutes. Add sauce and tomatoes, bring to a boil. Simmer 3-5 minutes or until chicken is cooked through. Stir in cream cheese.

Add chicken mixture to pasta mixture and stir in 1 cup mozzarella cheese and parmesan.

Spray 9x13 pan and spoon mixture into pan.

Bake 20 minutes or until heated through. Sprinkle with remaining cheese and bake 3 minutes until melted.

*Note: I also used less cheese and it seemed like there was still a lot