Heat olive oil in a large pot or Dutch oven over medium heat. Add onion and cook until softened, about 5 minutes.
Add garlic and cook for 1 minute more.
Add sweet potatoes, diced tomatoes, chickpeas, bone broth, smoked paprika, cumin, and cayenne pepper (if using). Bring to a boil, then reduce heat and simmer for 20-25 minutes, or until sweet potatoes are tender.
Stir in kale and cook until wilted, about 5 minutes.