Place Aidells Caramelized Onion Meatballs into a 4-quart slow cooker. Add the next seven ingredients (through pepper).
Cover and cook on low for 8 to 10 hours, or on high for 4 to 5 hours.
If using low, turn cooker to high. Gently stir in pasta. Cover and cook for 20 to 30 minutes more, or until pasta is tender. Stir in spinach, and olives.
Ladle soup into bowls. If desired, top servings with feta, lemon zest, and snipped fennel leaves.