Step 1
In a 6- to 8-quart slow cooker, combine the garlic, carrots, celery, onion, Parmesan rind, rosemary, chicken broth, olive oil, onion powder, garlic powder, red-pepper flakes, lemon juice, kosher salt, and several grinds of black pepper. Stir the ingredients together and cook on low for approximately 6 hours, until the carrots are tender and the flavors have fully melded.
Step 2
Increase the heat to high, then remove the lid. Add the chopped greens, stirring gently to incorporate. Pinch the sausage into small 1-inch pieces and drop them into the soup, submerging them in the broth. Replace the lid and cook for an additional hour, or until the sausage is thoroughly cooked. If using pasta or couscous, stir it in 40 minutes after the sausage has been added, and cook for another 20 minutes.
Step 3
Once the soup is finished cooking, discard the Parmesan rind and rosemary stem. Taste the soup and adjust the seasoning, adding more salt, black or red pepper, or lemon juice as desired. Serve the soup topped with grated Parmesan, if preferred.
Tip
Parmesan rinds, often available at well-stocked grocery stores alongside grated Parmesan, provide a cost-effective way to deepen the flavor of soups. These rinds can be stored in the freezer indefinitely, and there's no need to thaw them before use.