In a large pan, add the sausage, onion, and garlic. Roughly chop while the sausage is cooking. Cook over medium-high heat until the sausage is completely cooked through, about 8 to 10 minutes.
Once the sausage is cooked, remove it from the heat and drain the excess grease.
In a 6-quart slow cooker, add the chicken broth, crushed tomatoes, cooked sausage, and all of the seasonings.
Add the lid onto the slow cooker and cook on high for 2-3 hours or low for 4 to 5 hours.
Add the heavy cream, shredded parmesan cheese, and penne and cook for another 20 minutes.
Then add chopped kale and cook for another ten minutes.
Once cooked, serve and garnish with more cheese.
If you have a slow cooker with a sear setting, go ahead and saute your sausage, onions, and garlic in your slow cooker then proceed with the recipe. This allows you to omit the use of an additional pan.