Preheat oven to 350. Prepare a 9x13 pan by spraying with cooking spray. Set aside.
In a small saucepan, add chicken broth, onion, bell pepper, and celery seed. Bring to a boil then simmer for 10 minutes or until vegetables are soft.
In a large bowl, add pimentos, soup, and Velveeta. Pour the broth mixture over and stir to combine. Stir in 1 cup cheddar. Add cooked spaghetti and chicken and stir until everything is combined well.
Pour spaghetti mixture into prepared pan. Top with remaining 1 cup cheddar.
Bake for 30 minutes or until golden brown and bubbly.
Notes
If cooking your own chicken, make sure to season it first with salt, pepper, garlic powder, and onion powder. If using rotisserie or canned chicken, no need to season.
This is a great freezer meal! Divide into two smaller pans and freeze one for later.
You can use fresh celery (1/2 cup) in place of celery seed if desired.