Food Network teaches how to crush, slice and mince garlic. Peel off some of the papery skin from the garlic and then smash the head of garlic with the heel of your hand to loosen the cloves; if you only need a few cloves, leave the head intact and pull some off. Separate the cloves. To peel a clove, cut away the root end with your knife. Lay the flat side of the knife over the clove while holding the knife handle, then with the heel of your free hand carefully whack the knife against the garlic to separate the skin from the clove. To crush the peeled garlic, lay the flat side of the knife over the clove and smash it again. To slice peeled garlic, lay the clove flat on the cutting board and hold it with the fingertips of one hand, keeping them curled under. Using a rocking motion with the knife, make thin slices by moving the knife slowly across the clove. To mince peeled garlic, lay the flat side of a knife over the clove and smash it. Roughly chop the clove then move your free hand flat across the tip of the knife and use a rocking motion to chop the garlic until it’s finely minced.
Melt the stick of butter in a large pot over medium heat. Add the onions, garlic, bay leaves, thyme, and salt and pepper and cook until the onions are very soft and caramelized, about 25 minutes. Add the wine, bring to a boil, reduce the heat and simmer until the wine has evaporated and the onions are dry, about 5 minutes. Discard the bay leaves and thyme sprigs. Dust the onions with the flour and give them a stir. Turn the heat down to medium low so the flour doesn't burn, and cook for 10 minutes to cook out the raw flour taste. Now add the beef broth, bring the soup back to a simmer, and cook for 10 minutes. Season, to taste, with salt and pepper.
When you're ready to eat, preheat the broiler. Arrange the baguette slices on a baking sheet in a single layer. Sprinkle the slices with the Gruyere and broil until bubbly and golden brown, 3 to 5 minutes.
Ladle the soup in bowls and float several of the Gruyere croutons on top.
Alternative method: Ladle the soup into bowls, top each with 2 slices of bread and top with cheese. Put the bowls into the oven to toast the bread and melt the cheese.