Place the rinsed beans in a large bowl and cover with water by at least 2 inches. Let soak overnight, then drain and rinse well.
Heat the olive oil in a large skillet over medium-high heat. Add the sliced sausage and cook until browned, about 5-7 minutes. Use a slotted spoon to transfer the sausage to a 6-quart or larger slow cooker.
Add the onion, bell pepper, and celery to the same skillet. Cook, stirring occasionally, until softened, about 6-8 minutes. Add the minced garlic and cook for 1 more minute until fragrant.
Transfer the cooked vegetables to the slow cooker. Add the drained beans, chicken broth, bay leaves, thyme, smoked paprika, and cayenne pepper. Stir to combine.
Cover and cook on low for 8-10 hours or on high for 4-6 hours, until the beans are very tender.
Remove the bay leaves. For a creamier texture, use the back of a spoon to mash about 1 cup of the beans against the side of the slow cooker and stir them into the mixture.
Confirm the sausage has reached an internal temperature of 160°F (71°C) using a food thermometer.
Taste and season with salt and black pepper as needed.
Serve hot over a bed of cooked white rice, garnished with sliced green onions.