Butternut Squash Risotto for the Pressure Cooker
One of the things that has most amazed me since I joined Serious Eats and started digging deep into recipes and techniques is how frequently a cooking method that works perfectly in one application can fail so miserably in another. Take this pressure-cooked butternut squash risotto as a prime example.
Earlier this year, I did some tests on pressure-cooked grains, and found that in most cases, the pressure cooker didn't cut down drastically on cooking time, nor did it significantly improve the taste or texture of the cooked grains.
Meanwhile, I've had some success in the past with using a pressure cooker and baking soda to rapidly brown vegetables. It's a trick that I first saw published in the Modernist Cuisine cookbooks. In the book, they use the baking soda to increase the alkalinity of carrots, then cook them in a pressure cooker before turning them into a rich soup—the combination of high pH and high heat greatly speeds up the Maillard reactions that are responsible for much of the good flavor of deeply browned foods. Kenji has also used the technique with success in his French onion dip recipe.
Working on this recipe, though, turned all of those observations and tricks upside down. When it comes to risotto, the pressure cooker proved itself to be one of the best ways to cook rice grains: It's both insanely fast and low-maintenance. But when it comes to butternut squash, the pressure cooker did me no favors. And don't even get me started on the baking soda.
Actually, I take that back. I do want to get started on the baking soda. Here goes:
How to Make Butternut Squash Taste Like Pretzels (a.k.a. How Not to Cook Butternut Squash)
Seeing as how a pressure cooker and baking soda have the ability to enhance browning and also reduce cooking times, it seemed like a good thing to test out on butternut squash.
To start off, I followed Modernist Cuisine's instructions for making pressure-cooked caramelized carrots, substituting the squash instead. This is what I ended up with:
It's not attractive, but let's not go by appearance. After all, my goal was to turn this squash into a purée that I would then stir into the risotto. If it had been delicious, I would have used it regardless of its color.
The problem, though, was that it was not delicious. I didn't know it was possible for a vegetable to taste like a pretzel, but that's exactly what this tasted like. In some ways, it makes sense: Pretzels are traditionally dipped in a highly alkaline solution made with lye, which is why they turn such a deep brown color and develop that particular pretzel-y flavor when baked. Clearly, I had generated similar flavors with my pressure-cooked, baking-soda-spiked squash.
The other thing that was strange about this squash was how it completely lacked sweetness. Normally, caramelization—the process by which sugar breaks down into sweeter and more complex-tasting compounds—occurs at the same time as the Maillard reaction, so that those deeply roasted Maillard flavors are accompanied by a rich sweetness (just think of almost any good roasted root vegetable).* But somehow, the development of the sugars had been halted in my pressure-cooked squash, leaving the Maillard reaction to proceed at an extreme clip all by itself. The imbalance was disorienting.
You can read more about both the Maillard reaction and caramelization in Kenji's piece here.
As it turns out, this is a phenomenon that Kenji has written about before with regard to sweet potatoes. Just like the sweet potatoes that Kenji describes, butternut squash contains more complex starches that we don't necessarily perceive as sweet. As it cooks, those starches are broken down into simpler sugars that do taste sweet, but the process only happens at lower temperatures, between 130 and 170°F (54 and 77°C). Go above that, and the conversion of complex starches into simpler sugars comes to a halt.
That ends up being a problem in a pressure cooker: It gets too hot too quickly, and the flavor of the squash suffers as a result.
Having established that the pressure cooker wasn't going to work for the squash portion of this recipe, I switched to roasting. I even did some test batches with baking soda on the roasted squash. Without a doubt, it sped up browning, but I didn't care for the flavors it added to the squash—there was still that strange whiff of pretzel.
For this risotto, I knew I wanted a rich, sweet butternut squash flavor, and from my testing thus far, it was becoming clear that a classic roasting approach was going to be my way of getting there.
When Kenji made his sweet potatoes that I mentioned above, he cooked them for about an hour in that ideal low-temperature range before roasting them to guarantee that as much of the starch as possible would be converted to sweet sugars.
I could have gone that route here, too—and you absolutely should if you have the time or inclination—but because this recipe is a pressure-cooked risotto, part of what I felt it should promise is reduced cooking times. While I didn't want to sacrifice flavor in the name of speed, I also didn't want to develop a recipe that undid one of its coolest features (i.e., quick risotto-cooking time) by adding other lengthy procedures.
Before I explain what I did to achieve that, I think I should first stress that the single most important thing is the ripeness of the squash itself. No matter what other tricks I have up my sleeve, an underripe butternut squash is going to fall flat. It can sometimes be hard to tell when looking at a whole one, but ripe squash should feel heavy for its size and sound hollow when knocked with your knuckles. Most importantly, once you cut into it, the flesh of the butternut squash should be a deep orange color.
To pump up the sweetness while adding depth and layers of flavor, I took a two-pronged approach here. First, I roasted chunks of butternut squash with some garlic, sage, red pepper flakes, and half an apple, then puréed them together until smooth. The apple ties in so well with these flavors, and contributes a bit more sweetness without overtaking the squash flavor.
I also blended in a tiny bit of miso, just to balance those sweet notes with a hint of something salty, savory, and complex.
Meanwhile, I also tossed some smaller pieces of diced squash in olive oil and maple syrup, then roasted those as well until browned and crisp. These little bits of extra-sweet squash get stirred in at the end, while the subtle maple flavor again plays toward the autumn theme here.
The Magic of Pressure-Cooked Risotto
I've lost track of the number of times I've had someone tell me that they've never made risotto because they're intimidated by the idea of having to stand over the pot and stir continuously for well over half an hour. The saddest part is, that isn't even true. Yes, risotto needs to be stirred quite a bit, but you can put that spoon down. It's really not as labor-intensive as some people make it sound.
Still, it isn't the quickest of dishes, nor the most hands-off, which is probably why even I don't make it at home all too often.
The pressure cooker changes all of that.
The risotto starts out like most others: sweating some minced onions in oil until they're tender but not browned.
Then you stir in the rice, and continue to cook it until the grains are all coated in the oil and have toasted for a bit.
They'll start to look a little bit like tiny ice cubes: translucent around the edges and cloudy in the center.
Just about when you think the rice and onions will start to brown and burn if you let them go any longer, you add some wine, then cook it until the raw alcohol smell has mostly cooked off. This usually coincides with the wine fully evaporating, right about when you yet again need to add a liquid before the whole thing starts to burn.
In a more traditional recipe, this is the point when you start ladling in broth, little by little, and stirring often as you go, until the rice is finally cooked and suspended in a thick, creamy sauce.
But not with a pressure cooker!
Instead, we dump in all the remaining liquid, give it a quick stir, and then close the pressure cooker.
Then we bring the cooker up to low pressure (usually about 10 psi on most pressure cookers), and just let it go for five minutes. As soon as the time is up, you can quickly depressurize the cooker by running it under cold water (if it's not electric), or by using the pressure-release valve if it is electric.
When you open the cooker, it won't look like a proper risotto at first.
But once you give it a stir, the creamy sauce will form. I've recipe-tested this with two different pressure cookers, one a stovetop model and the other electric. In the stovetop one, the consistency was just about perfect once I stirred it and added the remaining ingredients. In the electric one, it was still just a little bit too loose, so I turned on the cooker's heating element and cooked it for a couple more minutes to get that creamy sauce. If for some reason it's too dry, you can loosen it with a splash of broth or water.
Then I stir in my squash purée.
The photos here are of the electric cooker, so it was just a tad too soupy at first, but it took only a couple minutes to bring it together.
For even more flavor, I decided to make a small amount of brown butter with frizzled sage while the risotto cooked.
I set the fried sage leaves aside to use as a garnish, and drizzled the sage-infused brown butter into the risotto, followed by the maple-roasted squash pieces.
I finished the risotto with grated Parmesan cheese, which helps thicken the sauce just a bit more, then spooned it onto plates.
Top it with those fried sage leaves and a little more cheese, and it's ready to go.
What you end up with is a risotto packed with layers of flavor. And, whether we're talking about clothes or food, isn't layering what fall is all about?