1

In a heavy-bottomed pot large enough to hold the soup, cook the onions in 3 tablespoons butter over medium heat, stirring for about 10 minutes, or until they release some of their liquid. Raise the heat to high and cook, stirring often, for about 30 minutes, or until the liquid runs dry and caramelizes on the bottom of the pot and the onions are melted into a compact tangled mass. Keep a close eye on the onions as they cook so that the liquid doesn’t run dry before it should and cause the onions to stick.

2

Add the sherry and water, bring to a boil, and cook, scraping the bottom of the pot with a wooden spoon to dissolve the browned—on juices, until the liquid is reduced by about half. Add the broth, season to taste with salt and pepper, and simmer.

3

Meanwhile, preheat the oven to 350°F. Spread the bread cubes on a sheet pan and toast in the oven, turning them every few minutes, for about 15 minutes, or until evenly browned. Leave the oven on. Alternatively, melt the 6 tablespoons butter in a large sauté pan or skillet over medium heat and sauté the bread cubes for about 12 minutes, or until evenly browned on all sides.

4

Return the soup to a simmer if it has cooled. Put 6 soup crocks on a sheet pan (so the soup doesn’t overflow onto your oven floor). Ladle the broth and onions into the crocks. Using half of the bread cubes, spread them evenly among the crocks. Top with half of the cheese. Spread the remaining bread cubes on top, and then the rest of the cheese. Bake for about 20 minutes, or until boiling broth starts to drip down the sides of the crocks.