Wash the chicken breasts and pat them dry with paper towels.

In a shallow dish, mix together the flour, salt, pepper, and garlic salt.

Coat each chicken breast quarter in the seasoned flour mixture, shaking off any excess.

In a skillet, heat the vegetable oil over medium-high heat.

Brown the coated chicken pieces on all sides in the hot oil.

Once browned, remove the chicken from the skillet and drain on paper towels to remove excess oil.

In the same skillet, add the sliced green pepper and onion.

Sauté until they are slightly softened.

Return the browned chicken pieces to the skillet, arranging them on top of the peppers and onions.

Pour the spaghetti sauce over the chicken in the skillet, ensuring all pieces are covered.

Cover the skillet with a lid and simmer on low heat for about 1 hour, or until the chicken is cooked through and tender.

Serve hot with spaghetti or your preferred side dish.