Preheat oven to 400 degrees
In a skillet, spray with non stick cooking spray and saute onion and 3 tbsp broth until onion is tender; set aside
Season chicken breasts with salt, pepper and Italian seasoning; cook in skillet until browned on both sides; set aside
Return onions to skillet and sprinkle with flour until onions are coated
Add 1/2 cup chicken stock and stir until mixture thickens
Pour into 9x13 baking dish and add chicken on top
Top each chicken breast with 1 oz cheese (shredded or sliced)
Bake for 20 minutes or until chicken is fully cooked
Spoon onion gravy over chicken breast and serve
FOR INSTANT POT: Put all ingredients into pot and cook on high for 20 min