Melt the butter in a large, heavy pan over medium-low heat. Add the onion, leek, and garlic. Cover and cook for about 5 minutes, stirring frequently, until the vegetables
start to soften.
Stir the flour into the vegetables
and continue cooking for 2 minutes. Add a little of the bouillon and stir well, scraping the bottom of the pan to mix in the flour. Bring to a boil, stirring, and slowly stir in the rest of the bouillon.
Add the carrots, celery, turnip, potato, thyme, and bay leaf. Reduce the heat.cover, and cook gently for about 35minutes, stirring occasionally, until the vegetables
are tender. Remove the bay leaf and the thyme sprigs.
4.stir the light cream into the soup and simmer over very low heat for 5 minutes. Add the grated cheese a handful at a time, stirring constantly for1 minute after each addition, to make sure it is completely melted.
Taste the soup
, adding salt if needed, and pepper to taste.
6.serve immediately in warm bowls, garnished with chopped fresh parsley.