Brown the sausage: In a large pot or Dutch oven, cook sausage over medium heat until browned and cooked through. Use a slotted spoon to transfer to a plate and set aside. Leave a little bit of drippings in the pot.
Sauté the veggies: Add butter, onion, carrots, and celery to the pot. Cook for 5–6 minutes, until softened. Stir in garlic and cook another minute.
Make the roux: Sprinkle flour over the veggies, stirring to coat. Cook for 1–2 minutes to remove raw flour taste.
Deglaze and season: Stir in soy sauce, hot sauce, dried herbs, and pepper. Gradually pour in chicken broth, whisking to combine.
Add potatoes and simmer: Stir in diced potatoes. Bring to a boil, then reduce to simmer for 15–20 minutes, until potatoes are tender.
Finish the soup: Lower heat, stir in heavy cream and cooked sausage. If desired, stir in cheddar cheese until melted.
Serve: Garnish with fresh parsley, extra cheese, or a sprinkle of red pepper flakes. Serve with crusty bread for dipping.