Lots of Mushrooms Lasagna

Mushroom Sauce: In saucepan, heat oil over medium-high heat; cook onion, garlic, carrot, celery and mushrooms, stirring, until no liquid remains, 15 minutes.

Add stock, salt, pepper and bay leaf; cook, stirring occasionally, until reduced by half, about 5 minutes. Add tomatoes and tomato paste; bring to boil. Reduce heat and simmer until thick enough to mound on spoon, about 20 minutes. Discard bay leaf. Set aside.

Cheese Filling: Meanwhile, in bowl, stir together ricotta cheese, egg, provolone cheese, parsley, salt and pepper. Set aside.

In large pot of boiling salted water, cook noodles until almost tender, 6 to 8 minutes. Drain; chill under cold water. Arrange in single layer between damp tea towels.

Spread 1 cup (250 mL) of the mushroom sauce in 13- x 9-inch (3 L) glass baking dish. Top with one-third of the noodles; spread with one-third of the remaining mushroom sauce, then half of the cheese filling. Starting with noodles, repeat layers once. Top with remaining noodles; spread with remaining mushroom sauce. Sprinkle with provolone and Parmesan cheeses. (Make-ahead: Refrigerate until cold. Cover with plastic wrap and overwrap with heavy-duty foil; freeze for up to 2 weeks. Thaw in refrigerator for 48 hours. Increase covered baking time by 15 minutes.)

Cover loosely with foil; bake in 375°F (190°C) oven for 30 minutes. Uncover and bake for 15 minutes or until bubbly. Let stand for 10 minutes before serving.