Cheesy Chicken Penne/Spaghetti

This was supposed to be made with penne, but I didn't have any so I used spaghetti.

12 oz pasta
2 T butter
1 onion diced
1 lb chicken breasts cubed
2 cups pured tomatoes
2 small tomatoes, diced
1/4 c cilantro
6 oz tomato paste
dash of salt and pepper
1/2 lb summer sausage sliced
1 cup jack cheese
1 cup sliced olives optional
chopped parsley

Cook pasta and set aside
Melt butter and cook onion and chicken until cooked. Add puree, tomatoes, cilantro, and paste. Season with salt and pepper. Simmer a few minutes.
Mix with pasta and pour into casserole dish. Top with sausage and cheese and olives. Bake about 20 min at 375.