Slow Cooker Chicken in Tomato Sauce

boneless skinless chicken breasts ((or tenders would work too))

butter ((divided))

olive oil

garlic powder

salt

pepper

fire-roasted crushed tomatoes ((1 can))

fire-roasted diced tomatoes ((1 can))

tomato sauce ((1 can))

Italian seasoning blend ((see notes))

large zucchini

Fresh basil