MIX broth, garlic powder, tomatoes, mushrooms and onions in 3 1/2-qt. slow cooker. Add chicken and turn to coat.
COVER and cook on LOW 7 to 8 hr.* or until done. Serve over spaghetti.
*or on HIGH 4 to 5 hr.
Tip: For thicker sauce, mix 2 tbsp. cornstarch and 2 tbsp. water. Remove chicken from cooker. Stir cornstarch mixture into cooker. Cover and cook on HIGH 10 min. or until mixture boils and thickens.
Serve with green beans and a tossed salad. For dessert serve mixed fruit.