Roll sausage meat into 1-inch meatballs. Heat 2 tbsp oil in large skillet set over medium heat; cook meatballs, in batches if needed, for 5 to 8 minutes or until browned all over. Transfer to plate; set aside.
Add remaining oil to same skillet; cook rosemary sprig and garlic cloves over medium heat for 2 to 3 minutes or until fragrant. Remove rosemary sprig. Add kale, and ¼ tsp each salt and pepper. Cook for 3 to 5 minutes or until kale is wilted.
Combine kale mixture, tomatoes, chicken broth, meatballs, roasted peppers, basil, and remaining salt and pepper.
In greased bowl of slow cooker, layer one-third each of the pasta, tomato mixture, ricotta, Parmesan, sliced mozzarella and shredded mozzarella. Repeat layers twice.
Cover and cook on High for 1 to 2 hours or Low for 3 to 4 hours or until pasta is tender and cheese is melted. Serve immediately.