Mountains of porcini and white mushrooms lend deep woodsy notes to this hearty vegetarian entrée, while a béchamel sauce offers all the richness of a meat-filled version. Use a food processor to finely chop the fresh mushrooms; they’ll cook more quickly. Members return to this recipe time and time again because its flavor far outweighs the fuss of assembling it. If you’re short on time, make just the filling or the whole dish a day ahead of time.
Recipe information
Yield
Makes 6 servings
Ingredients
FOR MUSHROOM FILLING
FOR SAUCE
Preparation
MAKE MUSHROOM FILLING
Step 1
In a small saucepan, bring water to a boil and remove the pan from the heat. Stir in the porcini and soak 20 minutes. Lift out the porcini, squeezing out excess liquid, and reserve the soaking liquid. In a sieve, rinse the porcini to remove any grit and pat dry; chop and transfer to a large bowl. Simmer the soaking liquid until reduced to about 1/4 cup. Pour the liquid through a sieve lined with a dampened paper towel into the bowl with the porcini.
Step 2
Quarter the white mushrooms, and in a food processor, pulse in 3 batches until finely chopped. Cut the zucchini into 1/4-inch dice. Chop the onion and mince the garlic.
Step 3
In a 12-inch heavy skillet, heat 1 tablespoon butter over moderate heat until the foam subsides and cook one-third of the white mushrooms with 2 tablespoons Sherry, stirring, until the liquid the mushrooms give off is evaporated and they begin to brown. Add the mushroom mixture to the porcini. Cook the remaining mushrooms in 2 batches in the butter with the remaining Sherry in same manner and add to the porcini mixture.
Step 4
In the skillet, cook the zucchini in 1 tablespoon butter until tender and stir into the porcini mixture. Cook the onion in the remaining tablespoon butter, stirring, until softened. Stir in the garlic, thyme, salt, and pepper and cook, stirring, until fragrant, about 30 seconds. Stir the onion into the mushroom mixture until combined.
MAKE SAUCE
Step 5
In a 3-quart heavy saucepan, melt the butter over moderately low heat and whisk in the flour. Cook the roux, whisking, 3 minutes and then whisk in the milk. Bring the sauce to a boil, whisking constantly, and simmer, whisking occasionally, 3 minutes. Stir in the 1 1/2 cups of Parmesan, the mustard, and salt. Remove the pan from the heat and cover surface with wax paper.
ASSEMBLE AND BAKE LASAGNE
Step 6
Preheat the oven to 375°F and butter a 13 by 9-inch baking dish.
Step 7
Spread 1 1/4 cups sauce in the baking dish and cover with 3 pasta sheets, making sure they don’t touch each other. Spread one-third of the filling over the pasta sheets and top with 3 more pasta sheets, gently pressing down layers to remove air pockets. Top the pasta sheets with one-third mozzarella. Continue layering in same manner with sauce, pasta sheets, filling, and mozzarella, ending with mozzarella (dish will be filled to rim). Spread remaining sauce over top and sprinkle with remaining 1/2 cup Parmesan. On a foil-lined large baking sheet, bake the lasagne in middle of oven until bubbling and golden, about 45 minutes. Let lasagne stand 20 minutes.
DO AHEAD
Step 8
The MUSHROOM FILLING may be made 1 day ahead and chilled, covered.
Step 9
The SAUCE may be made 1 day ahead and chilled, covered. Bring sauce to room temperature before proceeding.
Step 10
The LASAGNE may be baked 1 day ahead and chilled, covered. Bring lasagne to room temperature and reheat before serving.
