French Soap Dish: A Classic Savon de Marseille Recipe

A French soap dish is a shallow, savory baked custard inspired by the French dish clafoutis salé: eggs, milk, flour, and cheese baked with vegetables until tender and lightly golden. This flexible version uses zucchini, tomato, and Gruyère for a simple lunch or supper; the vegetables can be changed with the season.

Ingredients

1 tablespoon (15 ml) olive oil, plus a little for greasing
1 medium zucchini, about 8 ounces (225 g), cut into ¼-inch (6 mm) slices
1 cup (150 g) cherry tomatoes, halved
½ teaspoon (3 g) fine salt, divided
¼ teaspoon (1 g) freshly ground black pepper
3 large eggs
1 cup (240 ml) whole milk
¾ cup (95 g) all-purpose flour
½ teaspoon (2 g) baking powder
½ teaspoon (1 g) dried thyme, or 1 teaspoon (1 g) fresh thyme leaves
1 cup (100 g) grated Gruyère cheese, divided
2 tablespoons (8 g) chopped fresh parsley, plus extra to finish (optional)

Instructions

Heat the oven to 375°F (190°C). Lightly oil a 9-inch (23 cm) pie dish or similarly sized shallow baking dish. Set it on a rimmed baking sheet in case the batter bubbles over.
Warm the olive oil in a skillet over medium heat. Add the zucchini and cook for 5–6 minutes, stirring occasionally, until just tender and some moisture has evaporated. Season with half the salt and the pepper. Transfer to a plate and let it cool for a few minutes.
Whisk the eggs and milk in a large bowl until combined. In another bowl, whisk the flour, baking powder, thyme, and remaining salt. Add the dry mixture to the egg mixture gradually, whisking just until smooth. Avoid prolonged beating, which can make the baked texture tougher.
Fold in ¾ cup (75 g) of the Gruyère and the parsley, if using. Scatter the zucchini and halved tomatoes evenly in the prepared dish. Pour the batter over the vegetables, then sprinkle the remaining ¼ cup (25 g) cheese on top.
Bake for 32–40 minutes, until the center is set, the edges are puffed, and the top is golden. Because this is an egg dish, check the center with a food thermometer: the USDA FSIS safe minimum is 160°F (71°C). If the top browns before the center is cooked, loosely cover it with foil for the remaining baking time.
Let the dish rest for 10 minutes before slicing. It will settle slightly as it cools; serve warm, rather than piping hot, for neater portions.

Tips

Manage vegetable moisture: Cook zucchini first so it does not release excess water into the custard. If using watery vegetables such as mushrooms or spinach, sauté them and drain or squeeze out excess liquid before adding them.
Use room-temperature ingredients when convenient: Eggs and milk that are not very cold blend more easily and bake more evenly. There is no need to leave them out for a long time; 15–20 minutes is sufficient.
Choose a similar cheese: Comté, Emmental, or mild white cheddar can replace Gruyère in the same quantity. Feta is saltier and does not melt as smoothly, so use about ¾ cup (110 g) crumbled feta and reduce the added salt.
Keep the texture tender: Mix the flour in only until no dry streaks remain, and avoid filling the dish to the rim. A shallow baking dish gives the custard room to puff and cook through.

Serving Suggestions

Serve warm slices with a crisp green salad dressed with a sharp vinaigrette, or alongside lightly dressed bitter greens such as arugula or endive. For a more filling meal, add boiled new potatoes, crusty bread, or a bowl of vegetable soup. The dish also works at room temperature for a picnic-style lunch, provided it is kept chilled until serving and not left out for more than two hours.

Variations

For a Provençal-leaning variation, replace the zucchini with 1 cup (150 g) sautéed eggplant and add a pinch of dried herbes de Provence. You can also swap in 1 cup (150 g) cooked, chopped asparagus or broccoli; blanch firmer vegetables first so they become tender in the short baking time.

For a more substantial version, add ½ cup (75 g) finely chopped sautéed onion or ½ cup (75 g) cooked, crumbled bacon. Bacon is salty, so taste the mixture before adding all the measured salt. To make the dish gluten-free, use a cup-for-cup gluten-free flour blend that includes a binder; the result may be slightly softer and should be checked for doneness at the center.

Storage and Reheating

Cool leftovers promptly and refrigerate them in a covered container within two hours of baking. They keep for 3–4 days in the refrigerator. Reheat individual portions in a 325°F (165°C) oven for about 10–15 minutes, or microwave in short intervals until hot throughout; leftovers should reach 165°F (74°C). The texture is best when reheated gently. Freezing is possible for up to 2 months in an airtight container, though the custard may become a little watery after thawing; thaw overnight in the refrigerator and reheat thoroughly.

Frequently Asked Questions

Is a French soap dish actually made with soap?
No. The name is sometimes used for a savory French-style baked egg dish, not a household soap holder. This recipe is food made with eggs, milk, flour, vegetables, and cheese.

Is this the same as quiche?
Not quite. Quiche usually has a pastry crust and a richer custard, while this dish is crustless and uses flour mixed directly into the batter. It is closer in spirit to a savory clafoutis or a simple baked custard.

Can I prepare the batter ahead?
For the best texture, bake soon after mixing. You can cook the zucchini and grate the cheese up to a day ahead, then refrigerate them separately. Assemble with freshly mixed batter just before baking.

How can I tell when the center is done?
The middle should look set rather than liquid and should not wobble freely when the dish is moved. For food safety, confirm that the center reaches 160°F (71°C) with a food thermometer; the USDA FSIS minimum for egg dishes is 160°F (71°C).

Can I make it without baking powder?
Yes. The dish will still set, but it will be a little less puffed and airy. The baking powder is a small lift rather than the ingredient that holds the custard together.

Why did my savory custard turn watery?
Vegetables can release liquid as they bake, especially zucchini, mushrooms, and spinach. Sauté vegetables first, drain off excess moisture, and avoid adding them while hot enough to loosen the batter.

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Safety notes: safe minimum internal temperatures from USDA FSIS; raw and undercooked fish guidance from the U.S. FDA. Food safety notes

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