I have long been intrigued by the so-called "fifth flavor," umami. The concept of umami dates back to the late 19th century French chef Auguste Esoffier, who proclaimed that in addition to the widely recognized sweet, sour, salty and bitter flavors, there was a fifth flavor that our tongues could recognize; a savory flavor present in his veal stocks that didn't fit any of the other four flavor profiles.

But it wasn't until the early 20th century that a Japanese chemist discovered that the secret behind this fifth flavor was glutamic acid, which can be found in everything from aged cheeses, mushrooms, cured meats and fermented foods. He gave the fifth flavor the name "umami," which translates to "delicious" or "yummy" in Japanese.

Until the beginning of this century, the concept of umami was still somewhat controversial. Those naysayers should have tried this lasagna. With its mixture of meaty mushrooms, perfectly browned pancetta, aged Italian cheese and black truffle butter, it practically oozes umami.

This was my first time cooking with chestnuts, and I was quite pleased with the results. You can find jarred or frozen roasted chestnuts in many local grocery stores.

Black truffle butter, while not essential to this recipe, definitely adds a depth of flavor that I enjoyed. You can find it in specialty grocery stores, or in the cheese section at Whole Foods.

This recipe was originally printed in the New York Times "Pairings" column. Author Florence Fabricant suggests serving the mushroom lasagna with a glass of Pinot Noir.

Mushroom Lasagna
adapted from Florence Fabricant in the New York TImes

1/4 pound pancetta, sliced thin and slivered
2 tablespoons extra-virgin olive oil
1 medium onion, finely chopped
4 large garlic cloves, slivered
1 pound mixed mushrooms, sliced (I used shiitake, porcini and cremini)
12 chestnuts, roasted, peeled and quartered (many grocery stores sell these jarred or frozen)
12 sage leaves, slivered
Salt and pepper
2 1/4 cups milk, heated to nearly boiling
6 tablespoons unsalted butter or black truffle butter
1/2 cup flour
1/2 pound pasta for lasagna, preferably fresh, parboiled if dry
3 ounces grana padano or Parmigiano-Reggiano, grated.

1. Cook the pancetta in a large skillet over medium-low heat, stirring, until the fat starts to render. Increase the heat and cook a few minutes more, until the pancetta begins to brown and crisp. Remove the pancetta from the pan and transfer it to a dish.

2. Add the oil to the pan. Add the onion and garlic and sauté until softened. Stir in the mushrooms and sauté over medium heat until they wilt. Stir in the chestnuts and sage. Season with salt and pepper.

3. In a medium saucepan, melt 6 tablespoons butter or truffle butter on low heat. Whisk the flour into the melted butter. Cook briefly, then gradually whisk in the warm milk. Continue whisking and cooking until the sauce is thick and smooth. Season with salt and pepper.

4. Heat the oven to 350 degrees. Grease an 8-inch square baking dish. Cover the bottom of the dish with a film of the sauce, then cover it with a layer of pasta. Spread with half the mushrooms, scatter half the pancetta on top and sprinkle with a third of the cheese. Spread a third of the sauce on the cheese. Repeat the layers. Cover with the remaining pasta, spread with the remaining sauce and scatter the rest of the cheese on top.

5. Bake 40 to 45 minutes, until the top is lightly browned.

Serves 6.

Jessica Webster leads the Food & Drink section for the AnnArbor.com community team. You can reach her at JessicaWebster@AnnArbor.com.