Active Time

　　1¼ hours

　　Total Time

　　2½ hours

　　

Ingredients

Makes 12 first-course or 8 main course servings

　　

Béchamel Sauce

3 tablespoons unsalted butter

　　2½ tablespoons all-purpose flour

　　3 cups whole milk, heated

　　1 garlic clove, smashed

　　¾ teaspoon salt

　　⅛ teaspoon black pepper

　　

Mushroom Tomato Sauce

2 cups boiling-hot water

　　1 ounce dried porcini mushrooms (1 cup)

　　1 cup chopped onion (1 medium)

　　2 tablespoons extra-virgin olive oil

　　2 (14- to 15-ounce) cans diced tomatoes in juice

　　Pinch of sugar

　　2 tablespoons chopped fresh basil

　　½ teaspoon salt

　　

Assembling Lasagne

12 long ruffle-edged dried lasagne noodles (not no-boil)

　　5 ounces finely grated Parmigiano-Reggiano (1¾ cups)

　　

Béchamel Sauce

Step 1

Heat butter in a 2-quart heavy saucepan over moderately low heat until melted, then add flour and cook roux over low heat, whisking, 3 minutes. Add hot milk in a fast stream, whisking vigorously, and whisk in garlic and salt. Bring to a boil, whisking. Reduce heat and simmer, whisking occasionally, 10 minutes, then remove garlic and add pepper.

　　

Mushroom Tomato Sauce

Step 2

Pour boiling-hot water over porcini in a bowl and let stand until softened, about 20 minutes.Lift out porcini, squeezing excess liquid back into bowl, then rinse to remove any grit. Pour soaking liquid through a sieve lined with a dampened paper towel into another bowl. Chop porcini and add to soaking liquid.

　　

Step 3

Cook onion in oil in a 12-inch heavy skillet over moderate heat, stirring occasionally, until softened, 4 to 5 minutes, then stir in tomatoes with juice, sugar, porcini with soaking liquid, and 1 tablespoon basil. Simmer, stirring frequently, until tomatoes have broken down into a chunky sauce, about 25 minutes. Stir in salt and remaining tablespoon basil.

　　

Assemble and Bake Lasagne

Step 4

Cook lasagne noodles in a 6- to 8-quart pot of boiling salted water 8 minutes (noodles will not be cooked through), then drain and transfer to a bowl of cold water.

　　

Step 5

Put oven rack in middle position and preheat oven to 425°F.

　　

Step 6

Spread 1 cup béchamel on bottom of a buttered 13x9" baking dish, reserving remainder for last layer. Drain 3 lasagne noodles in 1 layer on a kitchen towel and arrange over béchamel in baking dish. Spread pasta in dish evenly with one third of mushroom tomato sauce and sprinkle with ⅓ cup cheese. Repeat layering of pasta, mushroom tomato sauce, and cheese twice, then cover with last 3 lasagne noodles. Spread remaining béchamel on top and sprinkle with remaining ¾ cup cheese.

　　

Step 7

Bake, uncovered, until lasagne is bubbling and top is browned, 30 to 35 minutes. Let stand at room temperature at least 15 minutes before cutting.

　　Cook's Notes:

　　· Béchamel and mushroom tomato sauces can be made 2 days ahead and cooled, uncovered, then chilled separately, covered. Bring sauces to room temperature before using.

　　· You can assemble lasagne 1 day ahead and chill, covered. Bring to room temperature before baking.