French Onion Soup Casserole
Updated Nov. 1, 2024
- Total Time
- 2 hours 15 minutes
- Rating
- Comments
- Read comments
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Ingredients
- 1baguette, cut into ½-inch slices (about 25 to 30)
- 9tablespoons butter, softened
- 9ounces Emmental cheese, finely grated
- 8medium yellow onions, thinly sliced (about 12 cups)
- 1tablespoon kosher salt, more to taste
- 1cup tomato purée
Nutritional analysis per serving (6 servings)
588 calories; 33 grams fat; 19 grams saturated fat; 0 grams trans fat; 9 grams monounsaturated fat; 2 grams polyunsaturated fat; 57 grams carbohydrates; 7 grams dietary fiber; 17 grams sugars; 19 grams protein; 1103 milligrams sodium
Note: The information shown is Edamam’s estimate based on available ingredients and preparation. It should not be considered a substitute for a professional nutritionist’s advice.
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Preparation
- Step 1
Toast the baguette slices and let them cool. Spread a generous layer of butter on each slice (you will need about 5 tablespoons), then lay the slices close together on a baking sheet and top with all but ½ cup of cheese.
- Step 2
In a large saucepan, melt the remaining 4 tablespoons butter over medium heat. Add the onions, season with salt and sauté, stirring occasionally, until very soft and golden, about 15 minutes.
- Step 3
In a 5-quart casserole, arrange a layer of bread slices (about ⅓ of them). Spread ⅓ of the onions on top, followed by ⅓ of the tomato purée. Repeat for two more layers. Sprinkle with the remaining ½ cup cheese. To avoid boiling over, the casserole must not be more than ⅔ full.
- Step 4
In a saucepan, bring 1½ quarts water to a boil. Add the salt. Very slowly pour the salted water into the casserole, near the edge, so that the liquid rises just to the top layer of cheese without covering it. (Depending on the size of your casserole, you may need more or less water.)
- Step 5
Preheat the oven to 350 degrees. Put the casserole on the stove and simmer uncovered for 30 minutes, then transfer to the oven and bake uncovered for 1 hour. The soup is ready when the surface looks like a crusty, golden cake and the inside is unctuous and so well blended that it is impossible to discern either cheese or onion. Each person is served some of the baked crust and some of the inside, which should be thick but not completely without liquid.
Private Notes
Comments
Took Jacques Pepin's suggestion and added 1/8 cup of both Worcestershire and Balsamic vinegar to onions as they started to cook. Added considerable depth and complexity vs recipe as written.
As expected, not exactly authentic french onion soup, but it yields uncanny favor from emmental and lightly caramelized onion. I've followed the recipe pretty much faithfully, and the result lacked liquid. It was moist but need more water to be called a genuine soup.
This was absolutely delicious. My only tweak would be to add the liquid before you add the top layer of cheese. It was really hard to pour all the liquid into my dutch oven without dousing the cheese (which makes browning much harder).
When I make this again, I would probably add the liquid to the pan first, then add a thin layer of breadcrumbs as sort of a barrier between the liquid and the top layer of cheese, so it browns properly.
This is now in the regular rotation. I doubled it up, mostly because we had onions that needed to be used. I added some balsamic vinegar based on other comments. Made it in a dutch oven sans lid since I don’t own a casserole dish large enough to accommodate 6 qts of this bubbling dish. Next time I’ll more faithfully cut the baguettes into 1/2” slices. Thicker slices end up floating more vigorously and damage its appearance. Probably use a whole can of purée next time rather than leave excess lying around and beef stock instead of water. Still, a win and better than soup, in my opinion.
A winter favorite in our house for many years. I like using red onions as well as white. I always wound up using more tomato sauce and cheese. Also, I didn’t top the bread slices with cheese until I laid them on top of the onion layer. It is a glorious bread pudding. I like the balsamic and Worcester tweaks suggested by another cook.
What sort of casserole dish does one use that can go on the stove for 30 minutes, then into the oven? Mine are Pyrex and can’t do stovetop. I have one cast iron casserole, but I think it is too deep (more like a soup/stew dish).
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