This isn't cream of garlic soup, but it has a creamy texture. I've done this one and it's great. As Julia says, "Because the garlic is boiled, its after-effects are at a minimum, and its flavor becomes exquisite, aromatic and almot undefinable."
From Julia Child's "Mastering the Art of French Cooking, Vol. I":
Drop garlic cloves in boiling water and boil for 30 seconds. Drain, run cold water over them and peel. Place the garlic and the rest of the ingredients in a 3-quart saucepan and boil slowly for 30 minutes. Correct seasoning.
3 egg yolks 3 to 4 T. olive oil
Beat the egg yolks with a wire whip in a soup tureen for a minute or until they are thick and sticky. Drop by drop beat in the olive oil for making a mayonnaise.
Rounds of hard-toasted French bread 1 cup of grated Swiss or Parmesan cheese
Just before serving, beat a ladleful of hot soup into the egg mixture by droplets. Gradually strain in the rest, beating and pressing the juice out of the garlic. Serve immediately, accompanied by the bread and cheese.