Rinse and sort the black-eyed peas, removing any debris.
In a skillet over medium heat, cook the bacon until lightly crisp. Transfer bacon to the slow cooker, reserving about 1 tablespoon of bacon fat.
In the same skillet, sauté onion in the reserved bacon fat until softened. Add garlic and cook for 30 seconds.
Add the onion and garlic mixture to the slow cooker.
Pour in broth, then add black pepper and smoked paprika. Stir gently.
Cover and cook on LOW for 6–8 hours or HIGH for 4–5 hours, until peas are tender.
Taste and adjust salt before serving. Add red pepper flakes if desired.