Winter Squash Gratin

A hearty dish for fall and winter

When autumn arrives, grocers start to feature colorful, thick-skinned winter squash. Their variety seems endless:  hubbard, acorn, kabocha, butternut, turban. And of course pumpkin (a name many people use generically for winter squash, though here in the US, “pumpkin” refers specifically to the big orange-hued squash that we use to make Jack-o’-lanterns—and pie).

You can often use the various types of winter squash interchangeably. Although their flavors and textures may differ somewhat, they all bear a close family resemblance. Certainly all of them work in a dish like this savory gratin, where the deep flavor of squash combines well with sharp Gruyère cheese.

This dish is almost a meal in itself, but it also makes a terrific side for roast fowl or baked ham. So it’s a handy recipe to have on hand when you start planning Thanksgiving and Christmas menus.

But you might want to prepare this dish right away—just to test it out, you know. You’ll be glad you did, because the flavor is wonderful. And you can pat yourself on the back for planning ahead.

Recipe: Winter Squash Gratin

There are two major steps in this recipe: First, roast the squash. Second, assemble the cooked squash with the other ingredients and bake the gratin. (I usually roast the squash a day ahead.)

I typically make this dish with acorn squash, but you can substitute another variety if you prefer. I think butternut, buttercup, or hubbard would probably all be delicious.

All gratins are more or less the same: You combine the main ingredient (squash, in this case) with cheese and cream or a Béchamel (white) sauce. This recipe is one I (lightly) adapted from James Peterson’s Vegetables. It makes enough to fill a gratin dish that holds about 7 cups and measures 8 x 11 inches (13 inches with handles).

Roasting the squash takes a hour, and can be done a day or two ahead. Prep time for the gratin itself is 15 minutes or so, and the dish takes 45 minutes or more to bake. So plan on at least 2 hours total (most of it unattended).

Leftovers keep for a few days if refrigerated in an airtight container. They’re good cold, but better when warmed in the microwave.

Ingredients

For the roast squash:

• ~2 pounds of winter squash (see Notes; if using acorn squash, about 2 smallish specimens—but you can use butternut or another variety; you want 2 pounds of flesh, or a bit less, after roasting)
• hot water

For assembly and cooking of the gratin:

• 1 medium onion (you need about ¾ cup, or a bit more, of thinly sliced onion)
• 2 garlic cloves
• 1 tablespoon olive oil (pure olive oil—the cheap stuff—works fine; or you can substitute butter, which is what the original recipe suggests)
• salt to taste (probably ½ to ¾ teaspoon Kosher salt, or about half that amount if using regular table salt; see Notes)
• ~1 teaspoon dried thyme
• ~1 tablespoon butter (for buttering the gratin dish; optional)
• ~2½ ounces grated Gruyère cheese (about one cup tightly packed; or to taste)
• ~1 ounce grated Parmesan cheese (maybe ¾  of a cup tightly packed; or to taste)
• the roast squash that you prepared
• freshly ground black pepper
• 1 cup heavy cream (may substitute milk, preferably whole milk)
• parsley for garnish, either sprigs or chopped (optional)

Procedure

For the roast squash:

1. Preheat oven to 375 degrees F.
2. If using acorn squash (my preference), cut the squash in half at the equator. Scoop out the seeds and the pulp that surrounds them. Place the squash halves flesh-side down in a rimmed dish just large enough to hold the squash. (If using another type of squash, you may need to cut it into wedges; scoop out and discard the seeds, and place the squash flesh-side down on the baking dish.) Add about a quarter inch or so of hot water to the dish (just enough to barely come up the sides of the squash pieces) and cover with aluminum foil.
3. Place the baking dish in the oven and set the timer for 50 minutes. The squash is done when its flesh is soft—test by poking a paring knife through the aluminum foil and rind into the flesh of the squash. If there’s resistance from the flesh, cook a bit longer. I usually need to cook the squash for an hour, but you don’t want to overcook, so start testing at 50 minutes.
4. Let the squash cool, then peel the skin off (with acorn squash, I can usually just pull it right off) or scoop the squash flesh out of the shell. Roughly chop the squash flesh into dice of ½ to ¾ inch.
5. You can use the roast squash immediately in the recipe, or refrigerate it in an airtight container for up to 2 days before proceeding with the rest of the recipe.

For assembly and cooking of the gratin:

1. Preheat oven to 375 degrees F.
2. Peel and thinly slice the onion. Peel and mince or thinly slice the garlic.
3. Heat a frying pan, preferably nonstick, on medium stovetop heat. When heated, add the olive oil. When the oil is hot (maybe 15 seconds—it will shimmer), add the onion and garlic. Season with salt and thyme, and sauté until the onion is translucent (roughly 8 minutes).
4. Meanwhile, butter the gratin dish (I’m not sure this is strictly necessary, but I like to do it). Grate the Gruyère and Parmesan cheese.
5. When the onion is ready, spread about half the onion-and-garlic mixture on the bottom of the gratin dish. Spread about half the roast squash chunks over the onion/garlic mixture, making an even layer. Add a few grinds of black pepper and about half the Gruyère cheese. Cover this with the rest of the onion/garlic mixture and the rest of the squash. Add more black pepper and the rest of the Gruyère cheese. Pour the heavy cream over the top, and sprinkle the Parmesan cheese on top of that.
6. Place the gratin dish in the oven (I usually put a rimmed baking sheet on the rack below the gratin dish in case there’s spillage) and set the timer for 35 minutes.
7. When the timer goes off at the 35-minute mark, check to see how the gratin is coming along. If you see liquid cream sloshing around when you tilt the gratin dish, it’s not done yet. Keeping baking, checking every 5 minutes or so. This gratin usually takes 45 minutes to bake in my oven, but I’ve had it take longer.
8. When done, the top should be golden brown. If not, run it under the broiler for a minute or two to brown the cheese. Sprinkle with parsley as a garnish, and serve.

Notes

• As mentioned, almost any kind of winter squash should work in this dish. Acorn squash has a particularly sweet flavor, so that’s what we tend to use.
• Exact quantities aren’t critical for the squash. You want about 2 pounds of cooked squash, so start with 2½ pounds or so of uncooked squash. Remember, you’ll be discarding the seeds and skin.
• For the dish shown in the photos, I used 28 ounces of cooked squash—i.e., a pound and ¾.
• You can substitute another hard Swiss cheese for the Gruyère, if you wish. Make sure it's one that melts well.
• I generally add salt to season the onions as they sauté (Step 3 of the assembly procedure). How much to use? I’ve suggested an amount, but you really need to rely on your own taste. Cheese adds additional saltiness to this dish, so I suggest erring on the side of too little rather than too much. It’s easy enough to add more salt (and pepper) at table.
• I like to use Kosher salt, but if you don’t have that on hand, you can use plain table salt (though I’d reduce the amount by about half since table salt is finer and more “condensed” than Kosher).
• Cream makes a very satisfying gratin, IMO—but it also adds calories and fat. You can substitute milk if you prefer (though if you use skim, the flavor will suffer).
• We tend to think of squash as vegetables. Technically, however, they’re fruits (because they contain seeds).
• The seeds in winter squash (with the exception of a few, like pumpkin) are generally inedible, as are the skins on all winter squash; thus the need to peel the skin before using. The skins and seeds of all summer squash are usually edible.
• Squash originated in the Americas, though many varieties are now grown around the world.

Seasonally Appropriate

“Oooh, winter squash!” said Mrs Kitchen Riffs. “I love it when those little punkins show up in the supermarket. You don’t see them for much of the year, so it’s always a treat when they make an appearance.”

“Yes,” I said. “We have to make good use of them while we can. Which is why I have another squash recipe coming up later this week. It’s Winter Squash, Corn, and Bacon Chowder.”

“Squash chowder?” said Mrs K R. “Nothing could be more appropriate!”

“What do you mean?” I asked.

“Well, our St. Louis Cardinals are playing the Boston Red Sox in the World Series,” said Mrs K R. “And when I think of Boston, I think of . . .”

“Chowder!” I said. “But why is squash chowder particularly appropriate?”

“Because the Cards are going to squash the Red Sox!” said Mrs K R.

“Impeccable logic,” I said. “Go Cards!”

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