Chicken Spaghetti Casserole

spaghetti (broken in half)

butter

onion (finely diced)

green bell pepper (diced)

white mushrooms (diced)

boneless, skinless chicken breast (cut into bite-sized pieces)

canned petite diced tomatoes (drained well)

Italian seasoning

kosher salt

pepper (to taste)

low-fat plain yogurt

cheddar cheese (shredded)

Parmesan cheese (grated)

mozzarella cheese (shredded)

paprika ((optional))