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Mushroom and winter squash gratin

Time1 hour 40 minutes
YieldsServes 8 to 10
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One morning recently, I woke up and realized summer was over. Though I live miles from anything like a forest, the cool, damp air carried a perfume that reminded me of a walk in the woods, feet shuffling through a deep thatch of wet, fallen leaves. I snuggled deeper into my comforter and dreamed about mushrooms.

Not just any mushrooms, of course. The fungus of my dreams tastes wild and woodsy. What too often ends up on my plate is flaccid and pallid. This is the result of nothing more than a failure to pay attention. All it takes to cook delicious mushrooms is just one simple trick: Do everything backward.

Normally, when we cook mushrooms, we build a flavoring base of butter or olive oil and shallots or garlic and then gently stew the mushrooms in it. Turn that around: Sear the mushrooms in a really hot pan and add the seasonings only after they’ve browned a bit. It sounds too easy, but just try it. Even the most common domestic mushrooms will taste rich and meaty, almost wild.

I came across this technique quite by accident. I was fixing dinner one night and focusing my attention on something else -- maybe grilled lamb chops or a roast chicken ... could have been a Laker game. I looked over and realized I had left the pan for the mushrooms over high heat and the butter was past foaming and even beginning to turn nutty.

I quickly dumped in the mushrooms and gave them a couple of tosses, thinking that would cool down the pan. Then I realized I’d forgotten to add the garlic and parsley, so in they went. A few more minutes and the dish was done.

I wasn’t expecting much. At best, I hoped nobody would pay the mushrooms any attention. But when I tasted them, they exploded with flavor. Where did you get these mushrooms? someone asked. What kind are they? Are they wild?

What happens is this: When the mushrooms hit the hot butter, they start to give off moisture. Add the seasonings at this point and they carry back to the mushrooms as that liquid concentrates and is reabsorbed. Furthermore, the process goes very quickly, so rather than stewing slowly, the mushrooms get a chance to brown a bit before they start to become limp.

I’ve since refined the technique. I now think it’s better to start the mushrooms on medium-high and then increase the heat once they’ve begun to sweat. I’ve found that salting them early helps draw out the moisture. And most recently, on rereading an old Edouard de Pomiane cookbook, I found he does almost the same thing, but covers the pan with a lid for the first couple of minutes -- that concentrates the heat even more.

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Vary the seasonings

MUSHROOMS prepared this way are terrific as a side dish, just served by themselves (a final gloss of butter and a couple of drops of sherry vinegar round out the flavor nicely). Vary the herbs and flavorings, maybe some rosemary (just a hint) or tarragon (as much as you want). Or you can use shallots in place of the garlic. And sometimes it’s nice to toss in some chopped, toasted hazelnuts for a little bit of crunch.

Try different mushrooms. White and brown buttons and portabellos are available everywhere -- they make up something like 90% of all mushrooms sold. Actually, they are all the same family of mushroom, Agaricus bisporus. But this doesn’t mean they are all the same.

According to Thomas Volk, a mycologist at the University of Wisconsin-La Crosse, originally all commercially raised Agaricus mushrooms were brown, but in the 1930s a white strain was found. Thought fashionable at the time, these came to dominate the industry, though they were selected primarily for color rather than flavor. When earthy-looking brown mushrooms made a comeback in the ‘80s, it was with a new strain that was chosen in part for the flavor, usually sold as cremini mushrooms.

Then, in the early ‘90s, growers found that they could get a premium for wild-looking, overgrown cremini mushrooms that already had opened out. They called them by a made-up name that was thought to sound Italian. Or rather, several made-up names -- you can find them labeled as “portobello,” “portabella,” “portobella” and “portabello” (for the record, the American Mushroom Institute prefers the last). So popular have these mushrooms become that normal cremini are being sold as “baby ‘bellos.”

Though portabellos are harvested only a week or so older than creminis, that is a long time in the life of a mushroom. The most obvious difference is size (figure four portabellos to the pound as opposed to 25 to 30 creminis). The extra maturity also means portabellos have begun to soften and the dark gills underneath have developed fully. Whether there is much of a difference in flavor is hard to say (but because of their size, portabellos are very nice grilled). If you are fastidious about appearance, remember that the mature gills tend to stain everything a rather dismal gray. If that bothers you, cut them off before cooking.

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Distinctive flavors

IN addition to these Agaricus mushrooms, Japanese markets also stock maitake, or “hen of the woods” mushrooms (Grifola fondosa), that have a deep, woodsy flavor and a pleasant, slightly tart edge. Fresh shiitake mushrooms are also common, but I find they have such a pronounced smoky aroma that they have to be used very carefully. And I still have not found a good use for enoki and oyster mushrooms, which even their most ardent fans describe as “mild flavored.”

Even if you’re limited to regular old button mushrooms, start with a variety of sizes. This way, when you cut them up you get a mix of shapes: Leave the smallest whole, cut the ones that are a little bigger into halves, cut the biggest into quarters, etc. All the mushrooms should end up roughly the same size so they will cook at the same rate.

This technique is also good as a starting point for preparing mushrooms in other dishes. I think of it as a kind of “intensifying” step -- like roasting tomatoes in olive oil. It doesn’t matter whether they are then used by themselves as a garnish, tossed with pasta or folded into a more complicated dish, they are improved by the process.

You can use them in a dish as simple as mixing the mushrooms with a little cream and using this to dress steamed potatoes.

Combine the two components while both are hot so the flavorings will penetrate the potato before the starch on the outside cools.

Or it can be something a lot more complex. Stew these intensified mushrooms in a mixture of prosciutto, leeks and creme fraiche, then fold them together with cooked spaghetti squash, add more cream, bake it, top with Parmesan bread crumbs and bake it again. The depth of mushroom flavor is magnificent.

The latter recipe is based very loosely on one by bestselling cookbook author Deborah Madison (in her version, she uses chanterelles and simply bakes them with squash and cream).

At first, combining mushrooms and spaghetti squash seemed odd (actually, considering my opinion of spaghetti squash, combining it with anything would seem odd). But the more I thought about it, I realized the bland, slightly bitter taste of the squash might be a good foil for the mushrooms. And because the spaghetti strands are so fibrous, they won’t go mushy the way real noodles might.

Think about it: Finally, something delicious to do with spaghetti squash. Pinch me, I must be dreaming.

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1

Heat the oven to 400 degrees. Cut the squash in half and remove the seeds. Place the squash cut-side down in a roasting pan and add about half an inch of water. Bake until the squash is easily pierced with a knife, about 1 hour.

2

Wipe the mushrooms clean, trim any hard stems and cut them into thick slices. Heat 3 tablespoons of the butter in a large skillet over medium-high heat until the foam has subsided and the butter turns a light hazelnut color. Add the mushrooms, sprinkle with three-fourths teaspoon salt, cover tightly and cook, tossing occasionally, until the mushrooms begin to glisten and give up their moisture, about 3 minutes.

3

Remove the cover, add the shallots, raise the heat to high and continue cooking, stirring constantly until the mushrooms are richly aromatic and soft, but not flaccid, about 3 minutes. Transfer the mushrooms to a bowl and set aside.

4

Reduce the heat to low and, without wiping out the pan, add the prosciutto. Cook on low heat for about 5 minutes. Meanwhile, cut away the dark green leaves of each leek, then cut in quarters lengthwise, leaving the leeks attached at the roots. Rinse thoroughly under cold, running water and slice thinly crosswise. Add the leeks to the prosciutto and cover tightly. Let the prosciutto and leeks sweat slowly, stirring occasionally until the leeks are quite tender, about 10 minutes.

5

Add the mushrooms back to the pan along with any liquid that has accumulated in the bottom of the bowl. Stir to combine with the prosciutto and leeks. Add the creme fraiche and continue to cook slowly, stirring occasionally, while you clean the squash.

6

Remove any scorched spots from the cut side of the squash. Hold one squash half over a large bowl, and with a fork, scrape out the strands, separating them as you work from one end of the squash to the other. When there is little left but the skin, empty the squash strands into the bowl. Repeat with the other half, adding it to the same bowl. Season the squash strands with 2 teaspoons salt and stir well to combine.

7

Add the mushroom mixture to the squash and again stir to combine. Transfer the mixture to a 2-quart gratin dish, mounding it slightly in the center. Add the heavy cream, shaking the pan gently to distribute the cream through the squash. The cream should just be visible around the edge of the squash. Bake until the cream is bubbling and beginning to darken around the outside, about 15 minutes.

8

While the gratin is baking, prepare the bread crumbs. Cut away the crusts of the bread and cut the interior into cubes. Process in a blender to make coarse bread crumbs; you should have about 2 1/2 cups. Add the Parmesan and pulse 3 or 4 times to thoroughly combine with the bread crumbs.

9

Scatter the bread crumbs evenly over the gratin, then dot with the rest of the butter. Return to the oven and bake until the top is golden brown, about 15 minutes. Cool slightly before serving.