I stumbled across half an unsliced loaf of dried-out sourdough in my kitchen the other day, and my first thought was of baked onion soup. When I was in college in California oh-so-many years ago, stale sourdough bread submerged in onion soup became one of my subsistence foods.

Although onion soup fit my budget when I was cooking on the cheap, the main reason I got hooked on it was that it makes a fine (and easy) wintertime meal. I’ve noticed through the years that onion soup sort of comes in and goes out of style, but it never goes away entirely. Perhaps that’s the measure of enduring popularity.

The name also changes as it goes through its incarnations. In addition to baked onion soup, I’ve seen it referred to as brown onion soup, onion soup au gratin, French onion soup and just plain onion soup.

Whatever it’s called, I first made it with my mother at my elbow. She had come to visit me in my college apartment and was appalled by what I was eating on a student’s budget. We spent several evenings with her teaching me how to make a variety of inexpensive and unchallenging meals.

In reading recipes for onion soups that are finished in the oven, I found some that call for a light and quick saute of the onions and some that skip the saute step altogether and go straight to the oven. I think either is a mistake. One of the charms of a good onion soup is a deep onion flavor, and you only get that by cooking the onion to the point that it is soft and transparent and the flavor turns sweet.

The bread also is important. You want a sturdy, tough-crust bread beneath the soup. Otherwise, you’ll get a spoonful of gooey dough on the first bite. Stale breads work best but fresh bread can be toasted or dried out in a low oven.

Baked onion soup

4 large onions, sliced

3 tablespoons butter

6-8 cups beef bouillon

splash of red wine (optional)

salt and pepper to taste

4 thick pieces of dried bread

1 cup grated Gruyere or other soft, white cheese

1/4 cup freshly grated Parmesan

Melt the butter in a soup pot and saute the onions for about 20 minutes, turning often, until they are wilted and transparent and just beginning to brown. Add the bouillon and wine, if desired, season with salt and pepper, and cook hard for 5 minutes. Lower the heat and simmer for 30 minutes.

Preheat oven to 350 degrees.

Place a piece of bread in each of 4 oven-proof soup bowls. If the bowls are deep, cut the bread in half and stack the pieces. The top of the bread should be just below the surface of the soup. Top the bread in each bowl with 1/4 cup of the Gruyere, then sprinkle with Parmesan.

Place the soup bowls in the oven for about 10 minutes, or until the soup begins to bubble and the cheese begins to brown.

Makes 4 servings