Squeeze the sausage out of the casings. Saute it up in a little olive oil, breaking it into pieces as it cooks. When it's almost done, add the minced garlic, diced onion, and sliced potatoes. Drain off excess olive oil.
When onions and potatoes are soft, add flour, stir to coat, and cook for another five minutes.
Add chicken broth and half and half. Let soup simmer all day, or keep warm in slow cooker or Instant Pot.
Before serving, add chopped kale and sliced onions and cook for another ten minutes (or set Instant Pot for three minutes) until kale and mushrooms are soft. Add pepper. Add salt if necessary, but the sausage and broth contribute salt already.
This makes a creamy soup. If you want it thicker, you can add a flour or cornstarch roux at the end and cook a little longer.