I love pasta dishes that are served with sauces-that-aren't-really-sauces. Not that browned butter or aglio e olio aren't really sauces, but they aren't really sauces in the same sense that, say, tomato sauce is a sauce or ragù Bolognese is a sauce.*
*If you're about to pipe in and say "but ragù is ragù, not sauce!" you can can it. We all know how much you know about Italian cuisine already.
Nope. They're simple emulsions made with a flavorful fat and pasta cooking water that serve the function of a sauce, coating the pasta in a thin, creamy sheen of flavor. Throw in some sautéed squash and some sage and you've got yourself a great 30-minute meal. It's a classic fall and winter dish that can be made right on the stovetop.
The beauty of a brown butter sauce is that you almost always have the ingredients on hand: butter and a splash of lemon juice. Some salt and pepper if you want to get technical, and okay, some frizzled minced sage if you want to get fancy. But that butter and lemon juice is really all you need. I'm gonna give you the instructions for how to make one. Ready? Heat the butter in a skillet until it's as dark as you want, toss in some sage (if you'd like), then add lemon juice.
Okay, it's a little bit more complicated than that, but that's the basic premise.
The hardest part of the recipe is peeling and dicing that squash uniformly. Luckily, we've got you covered in that department. Just check out our video and guide here.
Once that's done, I start by sautéing the squash in olive oil. I know this is a brown butter dish, but if I were to add the butter right from the start, it runs the risk of burning before the squash is completely done. I prefer to save the butter for later, adding it after the squash has browned and tenderized, which takes only about five minutes.
When the butter goes in, I add some minced shallot with it, then cook it all together, stirring constantly and keeping a careful eye on how dark the butter is getting.
If you've ever browned butter in a skillet for a recipe before, you know that as the butter heats up and its milk proteins slowly undergo the Maillard browning reactions, it can take on a wide variety of colors and flavors, a spectrum that goes from mild, milky, and pale to medium brown and nutty, all the way to nearly-black and roasty (and we're not counting actual black here because, trust me, except in rare circumstances, you don't want to make a sauce out of burnt butter). So brown butter sauces can vary accordingly in flavor and intensity, as well. That splash of lemon juice at the end not only adds brightness and flavor, it also plays the equally important role of regulating the sauce's temperature: when it hits the pan, everything cools down, halting the butter-browning process in its tracks.
To make mine, I cook it to a nutty blond before adding in my sage for a brief sizzle, followed by my lemon juice.
Brown butter sauces can also vary in texture. In some cases, like in a classic sole meunière, the sauce is served broken, with pools of glistening butterfat speckled with bits of browned butter solids to drag your fish through. In other cases, it's more thoroughly emulsified. When I'm making it for a dish like this butternut squash pasta, I like it to be emulsified into a creamy sauce that really coats the pasta and squash.
How do you make that emulsion? The secret is pasta water, the starchy cooking liquid left in the pot after your pasta is done cooking. It's the extra starch that does it. A few splashes of pasta water added to the browned butter as you toss it with the pasta adds just enough starch to keep the emulsion stable. That is, if there's enough starch in your pasta water to begin with.
In restaurants using fresh, handmade pasta cooked in a large pasta-boiling machine, that's not an issue. As batch after batch of pasta cooks throughout the night, that pasta water gets very starchy, making sauces simple. At home, most cooks are only cooking a single batch of pasta, and they're doing it in a large pot. What's more, modern pasta—extruded through teflon dies and dried at high temperatures—simply doesn't release as much starch as homemade or traditional dried pasta. In order to get your starch concentrated enough to really make a difference, I always recommend cooking dried pasta in a minimal amount of water—just enough to cover it by a couple inches.
As we've shown in countless recipes and tests, using a large volume of water for pasta is simply not necessary and can actually be worse for modern pastas. I cook the pasta, stirring occasionally to prevent sticking, until it's a little shy of al dente (about two minutes less than the package directions indicate). I drain it, reserving a couple cups of the starchy pasta water, and then I toss it and a few splashes of water with the squash, bringing it all to a violent simmer over the highest possible heat to allow the mechanical action of bubbles to do the work of emulsifying the sauce for me.
See how nice and creamy it gets? I keep simmering it hard until the pasta is fully cooked, splashing in extra pasta water as necessary to keep things nice and loose. If your pasta ever starts to stick, your sauce starts to look greasy, or you hear the ssssszzzzzzz sound of something being fried rather than the pthshsppphhsshpphtthtphps sound of a simmer, it's time to add a splash more pasta water.
Once the pasta is tender, I pull the whole pan off heat and add grated Parmigiano-Reggiano, tossing it all together and seasoning with salt and pepper.
It might not be quite as easy as opening up a jar of tomato sauce, but it's delicious and seasonal and hey—if you've got yourself an extra-large squash, you'll even have enough leftover to make some easy stovetop squash soup the next day.