In a mixing bowl combine meatball ingredients and shape into 1-inch meatballs.
In a large skillet add oil, turn to medium heat, add meatballs, and lightly brown on both sides. Note: Meatballs should not be cooked through, just lightly browned on the outside.
In the meantime, add the soup ingredients to the slow cooker, except the baby spinach and bacon, stir to combine. Add the browned meatballs, cover and cook on low 6 to 8 hour. Cook bacon until crispy, crumble into small pieces and set aside.
At the end of cooking time, add spinach and cook just until wilted, approximately 10 minutes. Add crumbled bacon pieces to the top of soup when serving.