To make the bread crumbs: Toast bread. Place in blender and grind into crumbs.
In a large bowl, combine ground turkey, bread crumbs, cheese, egg, garlic, salt, and pepper. Using clean hands, mix all the ingredients and form 24 small meatballs, about ⅛ cup each (2 tablespoons).
To cook onions: cook in microwave for 3 minutes to soften.
In a small, nonstick pan, heat olive oil over medium heat. Add garlic and sauté until lightly golden but not burned.
Pour into crock-pot garlic and oil, crushed tomatoes, softened onions, sugar, oregano, bay leaves, salt, pepper, and red pepper flakes. Mix well. Drop meatballs into sauce, press them down to cover completely with sauce. Set crock-pot to LOW heat for about 6 hours or HIGH heat for about 3 hours.