Wash and chop pepper. Peel and chop onion and finely chop garlic. Slice sausage into 1-inch pieces.
Heat large skillet over medium-high heat. Add sausage, stirring occasionally until browned, about 5 minutes.
Add sausage to slow cooker.
Return skillet to stove on medium heat. Add oil, onion, pepper and garlic and sauté for 3-4 minutes.
Transfer onions and garlic to slow cooker.
Add remaining ingredients to slow cooker and stir to combine.
Cook on high for 7-8 hours, until beans are tender and creamy and starting to break down.
Season to taste with salt and pepper and serve hot.