Twelve white mushroom caps in a round cream earthenware gratin dish, each filled with a domed pale green purée of green beans under a light brown crust of fine crumbs. — Mushroom caps filled with green bean purée and baked under crumbs.

Mushrooms Princesse (1907)

Name: Mushrooms Princesse
Prep time: 25 min
Cook time: 30 min
Total time: 55 min
Cuisine: French
Ingredients: 1 lb large white mushrooms (about 12); 1 tbsp olive oil; 1/4 tsp salt, for the caps; 1/8 tsp black pepper; 1/2 lb thin green beans (haricots verts); 1 tsp salt, for the bean water; 2 tbsp butter, for the beans; 1/2 cup canned flageolet beans, drained; 2 tbsp heavy cream; 1/8 tsp salt, for the purée; 2 tbsp fine dry breadcrumbs; 1 tbsp melted butter, for the tops

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Mushrooms princesse, after Escoffier’s stuffed mushrooms and bean purée of 1907: white caps baked with a dome of green bean and flageolet purée under a crust of crumbs.

By The Forgotten MenuPublished Oct 28, 2026

Recipe makes: 12 filled caps, 4 servings
Prep: 25 min
Cook: 30 min
Total: 55 min

The bean purée can be made a few hours ahead and kept in the refrigerator; warm it through before filling the caps, which then need about 20 minutes in the oven.

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Mushroom caps filled with green bean purée and baked under crumbs.

The story behind the recipe

Mushrooms with mashed string beans is how the English line on Air France’s Concorde card explains Champignons Princesse on its Paris to Washington menu. How the two met on the plate, it doesn’t say. This version fills the caps with the beans, using two recipes from Auguste Escoffier’s A Guide to Modern Cookery (London, 1907).

Why would a princess come with beans?

In Escoffier’s book, Princesse is usually a garnish of asparagus: his Poularde Princesse and his Crème Princesse both carry asparagus heads. One line shows another use. In his tournedos à la ménagère, the green beans to buy are “Haricot butter or ‘Princesse,’” and Princesse there is the name of a kind of bean. That makes the Concorde card’s English line less odd than it looks: string beans with a dish called Princesse may simply be beans living up to their name. The card doesn’t say so, and the link stays a possible one.

Escoffier’s stuffed mushrooms take fine, medium-sized mushrooms with the stalks removed, oiled and given five minutes in the oven, then filled with a dome of mushroom duxelles, dusted with fine crumbs and browned. His purée of French beans is the beans boiled, stewed in butter, rubbed through a fine sieve and loosened with half their bulk of creamy flageolet purée, made from the small pale green haricot bean. He thought highly of the main ingredient: “French beans are among the greatest vegetable delicacies,” he writes, and adds that they are almost always good, in spite of faulty preparation.

Making it today

Putting the bean purée into the caps in place of his duxelles is our choice; the card might equally have meant mushrooms and beans side by side. Canned flageolets, mashed with a little cream, stand in for his flageolet purée, and a food processor does the work of his sieve. His “somewhat fierce oven” becomes 400°F (200°C), a common setting in modern stuffed-mushroom recipes.

For the beans on their own there is Escoffier’s plain buttered version, French Beans (1907), which goes with the green beans on the Sultan of Morocco’s train menu of 1945. The card itself, with its offer to time the meal to the clocks of two continents, is read in What Did Concorde Serve on the Way to Washington in 1978?

Select some fine, medium-sized mushrooms; suppress their stalks; wash them, and dry them well. ...

A. EscoffierA Guide to Modern Cookery (London: William Heinemann, 1907), no. 2075, Champignons Farcis, p. 634, and no. 2159, Purée de Haricots Verts, p. 650

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Ingredients

For 12 filled caps, 4 servings. Quantities are shown as written.

Quantities as written here, for 12 filled caps, 4 servings.

Large white mushrooms (about 12)1 lb
Olive oil1 tbsp
Salt, for the caps1/4 tsp
Black pepper1/8 tsp
Thin green beans (haricots verts)0.5 lb
Salt, for the bean water1 tsp
Butter, for the beans2 tbsp
Canned flageolet beans, drained1/2 cup
Heavy cream2 tbsp
Salt, for the purée1/8 tsp
Fine dry breadcrumbs2 tbsp
Melted butter, for the tops1 tbsp

Ingredients as written here

1 lb large white mushrooms (about 12)
1 tbsp olive oil
1/4 tsp salt, for the caps
1/8 tsp black pepper
1/2 lb thin green beans (haricots verts)
1 tsp salt, for the bean water
2 tbsp butter, for the beans
1/2 cup canned flageolet beans, drained
2 tbsp heavy cream
1/8 tsp salt, for the purée
2 tbsp fine dry breadcrumbs
1 tbsp melted butter, for the tops

Equipment

Saucepan
Colander
Small frying pan
Food processor or fine sieve
Rimmed baking sheet
Small bowl
Instant-read thermometer

Instructions

Heat the oven to 400°F (200°C).
Pull or cut the stalks from the mushrooms, rinse the caps quickly and dry them well. Set them hollow side up on the baking sheet, season with the salt for the caps and the pepper, and brush them with the olive oil.
Bring a saucepan of water to a boil with the salt for the bean water. Top and tail the green beans and boil them for 6 to 8 minutes, until tender. Drain them well.
Melt the butter for the beans in the small frying pan over low heat and stew the drained beans in it for 8 minutes, stirring now and then, until they look dry and glossy.
Meanwhile, put the mushroom caps in the oven for 5 minutes. Take them out and tip away any juice that has gathered in the caps.
Mash the flageolet beans with the cream to a soft purée. Purée the green beans and their butter in the food processor until smooth, then mix in the flageolet purée and the salt for the purée.
Fill each cap with the bean purée, piled into a dome. Sprinkle the tops with the breadcrumbs and drizzle with the melted butter for the tops.
Bake for 12 to 15 minutes, until the crumbs are golden, the caps are tender when pierced with a knife and the center of the filling reads 165°F (74°C). Serve hot.

Nutrition

215calories per serving

Recipe makes: 12 filled caps, 4 servings
Servings: 4

Estimated per serving (4) from USDA FoodData Central values for white mushrooms, green beans, canned flageolet beans, butter, heavy cream, olive oil and breadcrumbs.

Recipe notes

When adjusting quantities

Allow about three medium-large caps a person. Keep the flageolet purée at about half the volume of the green bean purée, as Escoffier does.

Notes

Quantities mentioned in these notes don’t change when you adjust the servings.

Escoffier’s own filling is duxelles: chopped mushrooms and onion cooked dry, then simmered with tomato-flavored half-glaze, a little garlic and white wine. For mushrooms and beans side by side, bake the caps for 15 minutes with only oil, salt and pepper and serve the purée in a warm dish beside them. Dried flageolets, soaked and simmered until very soft, can replace canned. We set the quantities, oven setting and times. Chill leftovers within 2 hours and reheat them to 165°F (74°C). Contains milk and gluten.

Scaling changes the ingredients only; pan sizes and cooking times need their own judgment. To adapt this recipe further, try the recipe tool at TuneMyRecipe (opens in a new tab), our sister site.