French Onion Pasta is French onion soup meets spaghetti carbonara. It’s creamy, cheesy, and packed with sweet caramelized onion flavor.
Creamy French Onion Pasta
Surely pasta heaven includes Creamy French Onion Pasta, because this stuff is what dreams are made of. Cheesy, yes. True? Absolutely.
If you can imagine a true carbonara tasting even better, then you’d have this French Onion Pasta, because that’s essentially what this is.
We take all of the amazing parts of a carbonara sauce – the egg yolks, black pepper, and parmesan cheese – and intertwine it with the most intensely sweet and savory caramelized onions.
I also borrow elements of French onion soup and hit the caramelized onions with plenty of fresh thyme and a good dousing of cognac (my secret ingredient in French onion soup and this French Onion Chicken Skillet). If you can dream up something more delightful than this duo, let me know.
Traditionally spaghetti carbonara starts with bacon or pancetta, but I’ve skipped that in lieu of a more vegetarian-friendly version. While bacon and pancetta is yes, delicious (and I adore it in my traditional version of carbonara), I find in this version, it can overwhelm the flavor of the caramelized onions, which I want to be the star of the show.
If you feel so inclined to keep the meat, you are free to do so. I’d suggest sticking with pancetta since it’s not smoked and has a more mild flavor than traditional smoked bacon.
Ingredients in Creamy French Onion Pasta
Butter. You can’t caramelize onions without butter. A little goes a long way, and I’d suggest using unsalted butter so you can control the amount of salt in the end product.
Onions. Lots and lots of onions. It will seem like too much, I know. But it’s not trust me. As they slowly cook and release their starches, they will start to shrink.
Thyme. I love adding fresh thyme to French onion soup. It has a slightly citrus-y taste, and is super light and delicate, which I love.
Cognac. My secret ingredient in French onion pasta. This adds the most wonderful underlying savory/sweet flavor I can’t get enough of. You can usually find a super small bottle of it behind the counter at the liquor store.
Bucatini. I am obsessed with bucatini. What is bucatini? Bucatini pasta is basically a thicker spaghetti. It has a teeny tiny hole in the middle that allows sauce to get inside the noodle. I actually prefer it over spaghetti here. It’s a little bit heartier and clings to the pasta super well.
Egg yolks. You can find whole eggs in some carbonara recipe, but I prefer to stick to the yolks. I like the mouthfeel of them a little bit better, and they a richness to the sauce I adore.
Cream. Ok, ok. Cream is not a traditional ingredient in spaghetti carbonara. However, I like to add just a splash here for a little added richness. You can absolutely leave it out if you want to.
Pasta water. Pasta water is an essential ingredient in French onion pasta. Aside from the cream, it’s the one ingredient that literally makes the sauce. The starchy, salty pasta water has so much flavor and body to it, it makes the perfect creamy sauce.
Parmesan. You don’t need a ton of parmesan here, about 1/2-3/4 cup. I like to grate it so it incorporates into the pasta a little bit easier, but shredded is also fine. Make sure you buy a good-quality parmesan – ahem, like one that doesn’t come pre-shredded.
How to make Creamy French Onion Pasta
Caramelize the onions. Caramelizing the onions is the the most important step in this creamy French onion pasta. Because it’s the foundation of the flavor base, you really want to be diligent about caramelizing them just right. It’s a process that takes time and patience, but I promise, the end result is 100% worth it. The great thing is, it really doesn’t need much babysitting, so you can go about your business while the onions do your thing. Here’s how it’s done.
- Melt butter over a low heat.
- Add onions, salt, and just a pinch of sugar. Toss the onions in the butter and seasoning.
- Continue to cook the onions over a low heat until they start to brown and soften. Stir every 3-4 minutes to keep the onions from getting too brown in any one place.
- You may be asking, “How long does it take to caramelize onions?” And the answer is, it depends. Usually it takes mine anywhere from 20-30 minutes to completely caramelize. You know they’re done when they are a deep brown color, super soft, and taste super sweet.
Add the thyme and cognac. Once the onions are caramelized. I add the leaves of a few sprigs of thyme. Let it cook for a few minutes to infuse the caramelized onions with the thyme flavor.
Pour in the cognac. Turn the heat up to medium and let the cognac reduce and simmer until it’s reduce by half. Turn the heat off until you’re ready to assemble the pasta.
Cook the pasta. Once the onions are done cooking and the cognac has reduced, drop the bucatini in to salted boiling water. Cook until the pasta is just under aldente. (It will cook more when you toss with the sauce.)
Make the sauce. While the pasta cooks, whisk egg yolks, parmesan cheese, salt, pepper, and cream together in a medium bowl.
Assemble the pasta.
When the pasta is done cooking, use tongs to transfer the pasta to the pot with the caramelized onions and thyme. Reserve the pasta water.
While whisking, ladle in about 1/2 cup of starchy pasta water to the egg yolk and cheese mixture to bring the temperature of the ends up.
Turn the heat on the pan with the onions and pasta up to a low heat. Toss the pasta with the onions. While using the tongs to toss the pasta, slowly pour in the egg yolk and pasta water mixture. Continue to toss the pasta over a low heat to bring the sauce up to temperature. If needed, add a little bit more starchy pasta water to loosen the sauce up.
Season with plenty of salt and pepper to taste. Garnish with fresh thyme leaves and extra grated parmesan cheese.
Can I make this in advance?
While I wouldn’t recommend making creamy French onion pasta in advance, it does reheat pretty well. Because it’s a cream-based sauce, you want to SLOWLY heat up the pasta. I like to put it in a microwave-safe bowl and cover with damp paper towel before microwaving in 30-second bursts. Stir in between each cook time until the pasta is hot. Garnish with parmesan cheese.
Substitutions and Tips and Tricks for Recipe Success
- Be sure you don’t overcook your bucatini. Because the noodles will continue to cook when you toss the bucatini with the sauce, you risk the noodles becoming mushy if you cook them too long.
- Feel free to swap out pecorino or romano cheese for parmesan.
- When you toss the hot pasta with the sauce ingredients, but sure you don’t have the heat too high. If you have the heat too high, you risk scrambling the eggs.
- If you want to add bacon for a true carbonara, cook the bacon first, before the onions. Use the fat from the bacon to caramelize the onions. Remove the bacon and then toss with the pasta at the end.
- To add even more flavor, take the extra step of browning the butter before you add the onions. (See the process for browning butter, here.)
- 2 tbsp unsalted butter
- 2 medium onions, sliced
- 5 sprigs thyme, leaves removed
- 1 tsp sugar
- 1 tsp kosher salt, divided
- 1/2 cup cognac
- 3/4 lb bucatini noodles
- 3 egg yolks
- 1/4 cup heavy cream
- 3/4 cup grated parmesan cheese, plus more for garnish
- 1/4 tsp black pepper
- 1/2 cup pasta water
- Large skillet
- Large stock pot
- Mixing bowl
- Bring a large pot of water to a rolling boil. Season to taste with salt. It should be as salty as sea water.
- Add the butter to a large skillet. Turn the heat on medium-low. When the butter melts, add the onions, sugar, and 1/2 teaspoons salt. Toss the onions in the butter. Cook for 4-5 minutes until the onions begin to soften. Once they're soft, turn the heat down to low. Continue to cook the onions until they are very soft and a deep golden brown color. Stir every 4-5 minutes. It should take 20-25 minutes.
- While the onions cook, whisk the egg yolks, parmesan cheese, cream, black pepper and remaining 1/2 teaspoon salt in a medium bowl. Set aside.
- When the onions are done caramelizing, add the thyme. Cook for 1-2 minutes. Add the cognac and turn the heat up to medium. Simmer the onions and cognac until it's reduced by half. Turn the heat off and set aside.
- When you add the cognac, drop the bucatini into the pasta water. Cook until just under aldente. When the pasta is aldente, use tongs to transfer the pasta to the onions. Reserve the pasta water.
- Turn the heat back on a medium-low heat. Toss the pasta with the onions. Season with salt and pepper. Toss again.
- Slowly whisk in 1/2 cup of the pasta water to the egg yolk and parmesan mixture. Add the mixture to the pasta and onions. Use the tongs to contiunously toss the pasta with the sauce until the pasta is hot and the cheese has melted. Keep the heat on medium-low and stir constantly. If you don't do this, you risk scrambling the eggs. Remove from heat and season to taste with salt and pepper. Garnish with thyme and parmesan cheese.