Season both sides of the chicken with House Seasoning Blend and Italian Seasoning Blend; set aside.
Add sliced onions to the bottom of the slow cooker.
Place chicken on top of the onions.
In a small bowl, combine Better Than Bouillon Roasted Garlic base and 1/2 cup hot water; stir to dissolve.
Add Better Than Bouillon Roasted Garlic base, balsamic vinegar and diced tomatoes to the slow cooker.
Cover and cook on low for 6 hours or high for 3 hours.
With 30 minutes left of cooking time, add minced garlic and thyme; cover and finish cooking.