4 skinless, boneless chicken breast halves
(28 ounce) jar spaghetti sauce (such as Classico(R) Cabernet Marinara with Herbs)
1 (6 ounce) can tomato paste
1/4 pound sliced fresh mushrooms
1/2 yellow onion, minced
1/2 green bell pepper, seeded and diced
3 tablespoons minced garlic
1 1/2 teaspoons dried oregano
1/2 teaspoon dried basil
1/2 teaspoon ground black pepper
1/4 teaspoon red pepper flakes (optional)
Place chicken in a slow cooker; stir in spaghetti sauce, tomato paste, mushrooms, onion, bell pepper, garlic, oregano, basil, black pepper, and red pepper flakes. Cover.
Cook on Low until chicken is tender, 6 to 8 hours.