Preheat oven to 400. Drizzle the oil in a large casserole dish. Add the peppers and onions. Bake covered for 15 minutes to soften. Mix in half the seasoning.
Open each chicken breast to expose the inside. Divide the onion and pepper between the chicken breasts. Close the chicken breasts so the onions and peppers are inside. Place the chicken breasts in the casserole dish. Sprinkle the tops with the remaining seasoning.
Bake for 35-40 minutes until the chicken is fully cooked.
Optional: top each piece of chicken with cheddar cheese for the last 10 minutes of baking.
Notes
Prep Time: slice the onions and peppers when you bring them home from the store. They will last cut for several days in the fridge. To Reheat: place the chicken on a microwave plate and cover a paper towel. Heat for 1-2 minutes or until hot. You can also reheat in the oven at 350 degrees for 10-15 minutes or until it’s hot. To Freeze: if you are freezing several pieces, you will need to do a flash freeze. Then place the chicken in an airtight container. It will last for 1-2 months—Thaw before reheating.