Adapted from a recipe by Joël Robuchon
4 small heads of Living Lettuce, Boston Lettuce or similar lettuce, trimmed & cored, reserve 2 or 3 inner leaves for garnish
4 leeks, white and light green parts, cleaned and thinly sliced, about 1/2 pound, substitute shallots, green onions, a medium white or sweet onion
1 1/4 cups chicken or vegetable stock, low sodium
1 large egg
1/2 cup of milk
Pinch of freshly grated nutmeg
1/2 cup fresh or good quality frozen peas
6 tablespoons cold unsalted butter
Sea salt and freshly ground white or black pepper
Bring a large pan of water to a boil, add a pinch of salt and the lettuce. Blanch, stirring gently for 3 minutes. Drain the lettuce, rinse under cold water. Squeeze out any excess water. Transfer to a blender and purée until smooth. Transfer to a bowl.
In a large fry or sauté pan, melt 2 tablespoons of butter and add the leeks. Cover and cook over low heat, stirring often, until the leeks are softened, about 8 to 10 minutes. Transfer to a blender, add 1/4 cup of chicken stock and purée. In a medium bowl, whisk the egg, then whisk in the milk and leek purée. Season with a pinch of sea salt, pepper and nutmeg. Butter 4 small 8 oz cups, bowls or ramekins. Pour the leek custard into the cups and cover with plastic wrap.
Set a steaming rack in a pot large enough to hold the cups (use several pots if necessary). Add enough water to reach about 1 inch under the rack without touching it and bring to a boil. Set the cups on the rack. Cover the pot, reduce the heat and steam over low heat until the leek custards are barely set, about 20 minutes, but start checking after 15. The custards will still have a slight jiggle in the center.
While the custards are cooking, bring the remainder of the stock to a boil then reduce to a simmer. Whisk in the lettuce purée and simmer over medium heat for 3 minutes. Whisk in the crème fraîche and simmer for 3 more minutes. Remove from the heat and gradually whisk in 3 tablespoons of butter. Taste and adjust seasoning, if necessary.
In a small sauté or fry pan, melt a tablespoon of butter over medium heat. Add the peas with 1 tablespoon of water. Cook, stirring, until the peas are soft, but still retain their color and shape, about 3 to 5 minutes. Season with salt and pepper.
Finely shred the reserved lettuce leaves. When the leek custards are done remove the plastic wrap. Garnish with a few of the cooked peas and some shredded lettuce on top. Serve the custards with small individual pitchers of the lettuce soup, or one large one.