Brown the sausage in a large pot or Dutch oven over medium heat, breaking apart if crumbled. Drain excess fat, leaving a bit for flavor.

Add diced onion and minced garlic to the pot, sautéing for about 2-3 minutes until fragrant and translucent.

Stir in the diced potatoes and pour in the chicken broth. Bring to a simmer and cook for 10-15 minutes until the potatoes are fork-tender.

Stir in the chopped kale, heavy cream, and red pepper flakes (if using). Season with salt and pepper. Simmer gently for 5 more minutes.

Ladle the soup into bowls and serve warm with sides like crusty bread or garlic toast.