one-pan caramelized onion pasta
easy cozy comfort food
When I ran a poll on what this year’s easy-but-fancy holiday menu should star, beef tenderloin won out. I’ve been wanting to develop a beef tenderloin recipe here on What To Cook for years now so I was excited, and I cannot wait for y’all to try it! BUT I was also excited about the idea of developing an easy-but-fancy pasta dish, so I decided that this week, I’d follow that tenderloin-focused menu up with a new pasta that’s worthy of a special occasion (or any cold-weather weeknight!) and is EXTREMELY easy!
This pasta marries the rich, sweet, savory flavor of caramelized onions with the feels-like-magic ease of a one-pot pasta dish and the sauciness that every bowl of pasta deserves. Also, Boursin. It’s time for another Boursin recipe. It’s almost entirely hands off — it bakes in the oven! — so is ideal for entertaining, or for any night when you can’t park yourself in the kitchen for an hour to cook dinner. It’s also almost fully vegetarian. The only ingredient that isn’t is the anchovy paste, but I have a great sub for you in the notes section if needed!
PS, this recipe is a close cousin to one-pan creamy boursin pasta, which I posted about recently and so many of you asked for another version! Ask and you shall receive!
If you were hoping for a holiday entertaining menu starring pasta (or that was vegetarian friendly), make this dish the star of your show! Pair it with the merry and bright kale salad and bacon balsamic Brussels (omit the bacon if you want to avoid meat).
It would also be great with the beef tenderloin. Tenderloin, caramelized onion pasta, and kale salad would be a fabulous holiday meal.
This recipe is totally prep-ahead-able. Up to a day in advance, follow the recipe until just before you add the hot water. Cover the baking dish with foil and store it in the fridge. Pull it out, add the hot water and proceed with the recipe.
PS, for anyone that was hoping for an easy-but-fancy menu with seafood (the third option I gave in the IG poll!), see the “must have meat” note below the recipe for how to add shrimp to this pasta. One other seafood idea: You could swap the beef tenderloin in the OG menu with pan-seared scallops.
I love it when older WTC recipes make a resurgence, and I’ve gotten tagged in a ton of one-pan creamy Boursin pasta with shrimp pics recently. This meal comes together in a similar fashion so if you love that meal, you’ll love this one, too. And here are two more delicious one-pot pasta recipes to try or revisit: one-pot mushroom orzo carbonara and creamy chicken, leek, and sun-dried tomato orzotto!
Serves 6-8
Cook time: ~1 hour, 20 minutes (~20 minutes active, 1 hour inactive)
Tools:
Foil or a baking sheet
Tongs
Box grater or microplane
Ingredients:
1 pound spaghetti (uncooked)
1 pound yellow onion, very thinly sliced (this will be 1 large or 2 small onions, but weigh them to be sure — the amount is important! See notes for a slicing demo)
4 garlic cloves, minced
1/4 cup extra-virgin olive oil
1/4 cup tomato paste
2 tablespoons reduced-sodium Vegetable Better Than Bouillon (see notes if you can’t find it)
1 tablespoon anchovy paste (or 4 diced anchovies)
2 teaspoons dried Italian seasoning
1 1/2 teaspoons kosher salt
1/2 teaspoon red pepper flakes
4 1/4 cups hot water (as hot as your sink will go)
1 (5.2-ounce) package Boursin Garlic and Herbs
1 tablespoon any clear vinegar or lemon juice (I used champagne vinegar)
1/2 cup freshly grated Parm (ideally Parmigiano-Reggiano)
Optional, for serving: more grated Parm and red pepper flakes
Preheat the oven to 400°F.
In a 9x13-inch baking dish, layer (in this exact order!!!) 1 pound of spaghetti, 1 large or 2 small very thinly sliced (take your time and slice as thinly as you can!) yellow onions, 4 minced garlic cloves, 1/4 cup extra-virgin olive oil, 1/4 cup tomato paste, 2 tablespoons reduced-sodium Vegetable Better Than Bouillon, 1 tablespoon anchovy paste, 2 teaspoons dried Italian seasoning, 1 1/2 teaspoons kosher salt, and 1/2 teaspoon red pepper flakes.
Get in there with your hands and toss the onions with all of the pastes and oil and seasonings but DON’T toss the spaghetti — leave it on the bottom!
Pour in 4 1/4 cups of hot water (as hot as your sink will go!) down one corner of the dish so that it doesn’t wash everything off of the onions (don’t stress if it does a bit — it’ll be fine). Place 1 block of Boursin Garlic and Herbs over top. Cover the baking dish tightly with foil or simply place a baking sheet over top of the baking dish.
Bake for 45 minutes.
Carefully uncover the baking dish (but DO NOT stir or touch a thing!!!) and bake uncovered for an additional 10 to 15 minutes, checking at the 10-minute mark, until the onions are browned and soft.
Add 1 tablespoon vinegar or lemon juice and 1/2 cup freshly grated Parm and use tongs to toss everything together until combined and saucy. If a couple noodles are hard, no worries, it happens, just discard them. Taste. Need more salt? Add a pinch at a time until it’s perfect. Need more heat? Add some more red pepper flakes. Want more tang? Add more vinegar. Want it to be saucier? Toss in a little extra hot water. Keep tasting and seasoning until it’s delicious!
Serve and, optionally, garnish with grated Parm and/or red pepper flakes.
As it sits, the pasta will soak up the sauce. If you want to make it saucy again, add a splash of hot water and toss.
link to printer version
Must have meat: I only tested this recipe with Vegetable BTB and water, but I think adding beef bone broth would work really well here! Report back if you try it. Using reduced-sodium beef or chicken BTB would be delish, too. Beef stock would give it more of a French onion soup-y vibe. You could also add shrimp to this meal like we did in the Boursin pasta recipe I mentioned above. When there are 10 minutes of bake time left, add 1 pound of peeled and deveined shrimp on top. Drizzle the shrimp with a bit of extra-virgin olive oil and season with kosher salt and pepper. No need to evenly coat the shrimp — it’s OK if they’re not perfectly coated in oil. Return to the oven for another 10 minutes. Another way to add meat: Serve the pasta alongside some perfect pan-seared chicken breasts, skillet steaks, or any other meat you’d like.
Can’t find Better Than Bouillon? Use reduced-sodium stock (either vegetable, chicken, or beef) instead of the BTB and water, but warm the stock up first. 1 quart of stock is 4 cups, then just add 1/4 cup water. If you can’t find the reduced-sodium version of BTB, you can use “premium,” just cut the kosher salt back by a teaspoon and add more, if needed, at the end.
How to thinly slice an onion: Watch the “thinly sliced onion” demo in my knife skills guide! You’ll find it pulled out in a standalone clip at the bottom of the post (click here — it should shortcut you right to the demos section).
Prep ahead/love your leftovers: Like I said in the headnote, this meal is almost entirely prep-ahead-able. Read the “how to work it into the easy-but-fancy menu” section above the recipe for how to prep it ahead of time and still be able to serve it right out of the oven. The leftovers are also great for up to 4 days stored in an airtight container in the fridge. The noodles will absorb the sauce as they sit, so add splashes of water until it’s saucy again when you reheat in the microwave or on the stove.
Freezer-friendly: This is definitely freezable. I would probably freeze it as a casserole situation. Once cool, add the finished recipe to a freezer-friendly aluminum baking pan, sprinkle with mozzarella and/or Parm, cover and wrap it tightly with foil or plastic. Freeze. Bake it from frozen at 350°F until heated through (roughly 60 to 90 minutes). I’d bake it with foil on top for 60 minutes then remove the foil and bake for 10 to 20 minutes more until the cheese is golden and the dish is heated through.
Feeding kids: Cut back to 1/4 teaspoon (or even less) of the red pepper flakes if you’re feeding kids sensitive to spice.
Vegetarian: Already is EXCEPT for the anchovy paste. As a sub, you can use 1 tablespoon white miso paste plus 1/2 teaspoon soy sauce.
Dairy-free: Boursin makes a dairy-free version! Use that and a DF Parm instead. Kite Hill chive cream cheese would also be great here.
Gluten-free: Gluten-free noodles aren’t going to work as a direct sub (I think they will get mushy), but we can definitely make this recipe GF! I have not tested it this way, but here’s what I would do: Cook your favorite gluten-free pasta in a separate pot, but bake the onions and Boursin the exact same way, minus the pasta and water. Toss the cooked (and drained) pasta into the onion baking dish with a big splash of reserved pasta cooking water and toss until evenly coated. You could do the same thing with zoodles, aka zucchini noodles, or cooked spaghetti squash. To make the spaghetti squash, get a small one (2 1/2 pounds) cut it in half, scoop out the seeds, drizzle the insides with olive oil, salt, and pepper and place cut-side-down on a baking sheet. Roast while the onions and cheese roast. Let it cool, then use a fork to scrape out the strands directly into the onion/cheese pan. Toss to coat! Also, Better than Bouillon isn’t certified gluten-free. There are some GF alternative stock concentrates on the market like Herb-Ox, or use a GF stock instead!
Recipe inspo: I saw Plant You’s caramelized onion pasta for the first time this week and knew I had to do something similar but make it one-pan and not vegan. I used tomato paste and anchovy paste in my version and knew I’d seen that somewhere else before and finally remembered that I first learned to combine those two ingredients from Alison Roman’s caramelized shallot pasta.
Spaghetti: Bucatini, linguini, or another long noodle. I’m 99% sure you could use a short noodle like rotini or penne, but I didn’t test it so I’m nervous to say it works for sure. If you do it, please comment below!
Yellow onion: Red or white onion would work. Or 5 thinly sliced shallots. If you have an onion allergy… cook this recipe instead! It uses tomatoes and red bell pepper instead of onion and has similar vibes.
EVOO: Olive oil, avocado oil, or another neutral oil (but I really love EVOO here!)
Tomato paste: 8 ounces sun-dried tomatoes would be great here (drained, OR, if you really love tomato, you could use their oil in place of some or all of the EVOO)! If you have a tomato allergy, you could omit it.
Vegetable Better Than Bouillon and water: See the “can’t find BTB?” note above.
Anchovy: 1 tablespoon white miso paste plus 1/2 teaspoon soy sauce
Italian seasoning: A mixture of dried parsley, oregano, and basil. Or just use only one or two of those, if it’s what you’ve got.
Red pepper flakes: 1/2 teaspoon aleppo pepper flakes or paprika, 1/8 to 1/4 teaspoon cayenne (it’s spicier than red pepper flakes!), or omit
Garlic: 4 cubes of crushed garlic or 1/2 teaspoon garlic powder
Boursin: 5 to 8 ounces of any other creamy cheese you like. Feta, goat cheese, even cream cheese will do the trick. But if you don’t use the garlic and herbs cheese, you’ll need to add an extra teaspoon of Italian seasoning, dried oregano, or dried thyme.
Any light-colored vinegar: Lemon juice or a clear vinegar like champagne, white wine, or apple cider vinegar
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Editor: Molly Ramsey
One more note! Better than Bouillon isn’t certified gluten-free. There are some GF alternative stock concentrates on the market like Herb-Ox, or use a GF stock instead!
Made it with shellbow pasta tonight and it turned out great! Didn’t need to add more water or change anything else.