The following recipe for cream of onion soup comes from “The Dewey Cook Book,” which was published as a fundraiser by the Women’s Auxiliary of the YMCA in Montpelier, Vt. The title honors Adm. George Dewey, and the frontispiece shows his birthplace in Montpelier. The cookbook was published in 1899 when Dewey returned home from the Pacific to a succession of celebrations.
The first step is slow and tedious but essential to caramelize the natural sugars in the onions and bring out their flavor. So have a book or a phone handy to amuse yourself. You will need a thick-bottomed pan. I use a 9½ inch-wide pot with a nonstick coating. If you double the recipe, you will need a large frying pan for more surface area for water to evaporate from the onions. Brown the onions in the oil and butter over medium-low heat, stirring occasionally and adjusting the heat as needed so that the onions turn golden brown but don’t burn.
Add the sugar if you are using it to help the browning process. It takes me about 45 minutes to brown the onions. If you want to puree the soup, you should let the onions cool a little and then run them through a food mill. Or you could puree the soup with a stick blender just before adding the milk. I prefer the texture without pureeing.
Once the onions are brown, add the chicken broth and raise the heat to bring the soup to a boil, then lower the heat and simmer for 30 minutes. (If you are making this soup ahead of time, you should stop here.)
Stir in the milk or cream. To prevent curdling the eggs, stir about half a cup of the hot soup into the eggs while stirring briskly. Stir in another ½ cup of hot soup and then stir the egg mixture back into the soup over low heat. Cook briefly, just until thickened a little. Taste and add salt and pepper as needed.