Add the sweet potatoes, onion, garlic, bell pepper, chickpeas, diced tomatoes, and vegetable broth to the slow cooker.
Stir in the cumin, smoked paprika, cayenne, salt, and black pepper until evenly combined.
Cover and cook on low for 6 to 7 hours, until the sweet potatoes are very tender.
Stir in the peanut butter until it melts into the broth and thickens the stew.
Add the spinach and stir until it wilts, about 5 minutes.
Taste and adjust salt or cayenne if needed.
Serve hot with chopped peanuts and cilantro sprinkled on top.