1. In a large soup pot over medium-high heat, cook the Italian sausage until browned and fully cooked, breaking it into small pieces as it cooks. Remove the sausage with a slotted spoon and place it on a paper towel-lined plate. Leave about 1 tablespoon of the drippings in the pot.

2. Add the butter to the pot. Once melted, stir in the onion and celery. Cook for 4 to 5 minutes until softened, scraping up any browned bits from the bottom of the pot.

3. Add the garlic and flour, stirring constantly for about 2 minutes to cook out the raw flour taste.

4. Slowly pour in the chicken broth while whisking continuously until the mixture is smooth and free of lumps.

5. Stir in the half-and-half, Worcestershire sauce, crushed red pepper flakes, diced potatoes, and cooked sausage.

6. Increase the heat and bring the soup to a gentle boil. Reduce the heat to medium-low and let it simmer with the lid slightly open for about 15 minutes, or until the potatoes are tender and the soup has thickened.

7. Stir occasionally to prevent sticking and adjust seasoning with salt and black pepper before serving.