Old-Fashioned Onion Soup

Four ingredients and a slow cooker are all you need for this stripped-down onion soup. Three pounds of thinly sliced onions cook in melted butter and chicken broth with cubed French bread stirred right into the pot. The bread breaks down over hours of slow cooking, thickening the broth into something rich and silky without any flour or roux.

This is a set-it-and-forget-it recipe. On low, the onions melt into the broth over 10 to 18 hours, turning sweet and deeply caramelized without you standing over a stove stirring. The long, gentle heat does all the work that would normally take 45 minutes of active stovetop caramelizing.

Stir well during the last hour. By then the bread has dissolved into the liquid and the onions are completely soft. The soup should be thick and glossy. If it’s too thick, add a splash more broth to thin it out.

Pro Tips

• Slice the onions as thin and uniform as you can. Thick pieces won’t break down fully and you’ll end up with uneven texture.
• Yellow onions give the best balance of sweet and savory. Vidalia or other sweet onions will make a sweeter, milder soup.
• Ladle into oven-safe bowls, top with a slice of French bread and Gruyère, and broil for a classic French onion presentation.

Variations

• Add a splash of dry white wine or sherry during the last hour for more complexity.
• Use beef broth instead of chicken for a darker, more robust version closer to traditional French onion soup.