Step 1

Prepare the Broth: In the large pot, heat the butter over medium heat until it is melted and begins to brown. Add the onions and cook over medium heat, stirring occasionally, until they are soft and browned (about 20 minutes). Onion soup, unsurprisingly, is all about the onions. Make damn sure the onions are a nice, dark, even brown color.

Step 2

Increase the heat to medium high and stir in the port and the vinegar, scraping all that brown goodness from the bottom of the pot into the liquid. Add the chicken stock. Add the bacon and bouquet garni and bring to a boil.

Step 3

Reduce to a simmer, season with salt and pepper, and cook for 45 minutes to an hour, skimming any foam off the top with the ladle. Remove the bouquet garni.

Step 4

The Croutons and Cheese: When the soup is finished cooking, ladle it into the individual crocks. Float two croutons side by side on top of each. Spread a generous, even heaping amount of cheese over the top of the soup. You want some extra to hang over the edges, as the crispy, near-burnt stuff that sticks to the outer sides of the crocks once it comes out from under the heat is often the best part.

Step 5

Place each crock under a preheated, rip-roaring broiler until the cheese melts, bubbles, browns, and even scorches slightly in spots. The finished cheese should be a panorama of molten brown hues ranging from golden brown to dark brown to a few black spots where the cheese blistered and burned. Serve immediately—and carefully. You don’t know pain until you’ve spilled one of these things in your lap.

Step 6

If your broiler is too small or too weak to pull this off, you can try it in a preheated 425°F (220°C) oven until melted. A nice optional move: Once the mound of grated cheese starts to flatten out in the oven, remove each crock and, with a propane torch, blast the cheese until you get the colors you want.

Step 7

Half-Assed Alternative: Your broiler sucks. Your oven isn’t much better. Can’t find those ovenproof crocks anywhere. And you ain’t ponying up for a damn propane torch, ’cause your kid’s got pyromaniac tendencies. You can simply toast cheese over the croutons on a sheet pan, and float them as garnish on the soup. Not exactly classic—but still good.

Step 8

Note on the Propane Torch: This is a very handy-dandy piece of equipment, especially if your stove is not the greatest. Nearly all professional kitchens have them; they’re not very expensive and they can be used for a variety of sneaky tasks, such as easily caramelizing the top of créme brûlée or toasting meringues.