Melt butter over medium heat in a large saucepan or stock pot. Add the onion and cook until it's translucent.
Next add the potatoes, broccoli salt, thyme, basil, pepper and chicken stock. Cover, reduce heat and cook until potatoes are just tender; about 10 minutes.
Mix the thickening ingredients well so there's no lumps (thinkening is optional) and whisk into the soup. Bring to a boil and cook for 5 minutes to cook the flour.
Stir in the cream and shredded cheese. Simmer until cheese melts.