Pat the turkey breast dry
Season with salt, pepper, garlic powder, onion powder, and herbs
Optional: rub with butter or olive oil
Place sliced onions, carrots, or celery in the bottom of the slow cooker
Set the turkey breast on top of the vegetables, skin side up if applicable
Add a small amount of broth or water to the bottom
Cover and cook on low for 5 to 7 hours, or on high for 3 to 4 hours
Cook until the internal temperature reaches 165°F
Remove the turkey breast from the slow cooker
Let it rest for 10 to 15 minutes before slicing
Slice and serve