Layer the base: Add sweet potatoes and sliced onion to the bottom of the slow cooker. This creates a bed that keeps the chicken elevated and helps everything cook evenly.
Mix the seasoning: In a small bowl, whisk together olive oil, garlic, smoked paprika, cumin, thyme, cinnamon (if using), salt, and pepper.
Stir in tomato paste for extra richness if you like.
Season the chicken: Place the chicken in a bowl and coat it with the seasoning mixture. Make sure each piece is well covered.
Add the liquids: Pour the chicken broth over the sweet potatoes and onions. Nestle the seasoned chicken on top.
Cook: Cover and cook on Low for 6–7 hours or High for 3–4 hours, until the chicken is tender and the sweet potatoes are soft but not falling apart.
Finish with acidity: When done, stir in lemon juice or apple cider vinegar.
This brightens the flavors and balances the sweetness.
Optional greens: If adding spinach, stir it in during the last 5 minutes until wilted. Add bell peppers during the final hour if you prefer them tender-crisp.
Taste and adjust: Check for seasoning and add a pinch more salt or pepper if needed. Garnish with fresh herbs and serve.