Kale Soup with Portuguese Sausage

1 quart beef stock

1 quart chicken stock

2 (14.5 ounce) cans white beans, rinsed and drained

½ onion, unchopped

3 cloves whole garlic cloves

2 teaspoons kosher salt

1 teaspoon ground black pepper

2 sprigs fresh thyme

½ pound Portuguese andouille sausage, sliced

2 bunches kale, torn into small pieces

1 stalk celery, diced

2 carrots, chopped, or more to taste

¼ teaspoon garlic salt, or to taste

Combine the beef stock, chicken stock, beans, onion half, garlic cloves, salt, black pepper, and thyme in a slow cooker; cook on Low for 8 hours to overnight. Remove and discard the onion and garlic.

Switch slow cooker to Keep Warm setting. Add the andouille sausage to the stock mixture; continue cooking until you can smell the sausage, about 1 hour. Stir the kale, celery, carrots, and garlic salt into the soup; cook until the carrots are tender, about 1 hour more.