Crumble the sausages into a soup pot. Over medium-high heat, cook until browned (about 10 minutes). Transfer to a paper towel lined plate. Leave the fat in the pot, but if it's more than about a tablespoon, drain some of it out.
Add the butter to the pot and once it's melted, add the onion and celery and sauté for 4-5 minutes. Scrape up any brown bits from the bottom of the pot.
Stir in the garlic and flour. Cook for about 2 minutes, breaking it up with your spoon/stirring it as you go along. This step cooks the raw flour flavor out.
Slowly whisk in the chicken broth until all the flour has dissolved and there's no lumps.
Stir in the cream, Worcestershire sauce, red pepper flakes, potatoes, and add the sausage meat back to the pot. Increase the heat to high and bring the soup to a boil, then reduce the heat so it's bubbling but not boiling like crazy (medium-low heat works with my cast iron pot and gas stove). Cover the pot with the lid slightly open.
Let the soup simmer for about 15 minutes or until the potatoes are tender and the soup has thickened up to your liking. I like to stir it a few times to ensure nothing is sticking and that the stove's temperature is still correct.
Turn the stove off, and then stir in the cheddar gradually. If the soup seems too thick, add in a splash more chicken broth (milk or cream works too).
Season with salt & pepper if needed.