I build this pasta around deeply caramelized onions—jammy, sweet-savory strands that melt into a glossy sauce, finished with Parmesan, a splash of acidity, and a hint of heat. I keep it simple but layered so every twirl tastes rich without feeling heavy.

Why You’ll Love This Recipe

I slowly caramelize a heap of onions until they’re mahogany and jammy, I deglaze to capture every browned bit, and I use starchy pasta water to make a silky, restaurant-style emulsion. I finish with cheese and a squeeze of lemon so the sauce stays balanced and bright.

Ingredients

(Here’s a tip: Check out the full list of ingredients and measurements in the recipe card below.)

• Olive oil

• Unsalted butter

• Yellow onions, thinly sliced (a big mound)

• Garlic, finely sliced or minced

• Fresh thyme or rosemary (optional)

• Red pepper flakes (optional)

• Dry white wine or low-sodium stock (for deglazing)

• Balsamic or sherry vinegar (just a splash)

• Pasta (bucatini, tagliatelle, or spaghetti)

• Finely grated Parmesan (or Pecorino)

• Fresh lemon (zest and juice)

• Fresh parsley or chives, chopped (optional)

• Fine sea salt and black pepper

• Optional umami boosters: 1–2 anchovy fillets or 1 teaspoon white miso

• Optional creaminess: mascarpone or a small splash of heavy cream

Directions

1. I prep the onions first: I halve them pole-to-pole, trim the ends, peel, and slice into thin half-moons.

2. I start them low and slow: in a wide heavy skillet, I warm olive oil and butter over medium-low. I add the onions with a big pinch of salt and cook, stirring every few minutes, until soft and translucent, about 15 minutes.

3. I caramelize patiently: I continue cooking 20–30 minutes more, adjusting heat to prevent burning. If brown bits build up, I splash in water and scrape them back into the onions. I want them deep golden and jammy.

4. I build flavor: I push the onions to one side and add garlic, red pepper flakes, and herbs to the cleared spot for 30–60 seconds. If I’m using anchovy or miso, I stir it in now until dissolved.

5. I deglaze: I pour in wine (or stock), scraping up all the browned bits, and simmer until nearly evaporated. I add a small splash of vinegar for brightness.

6. Meanwhile, I boil the pasta in well-salted water until just shy of al dente. I reserve about 1 1/2 cups of the starchy water.

7. I make it saucy: I add a big splash of pasta water to the onions and bring to a lively simmer so it emulsifies.

8. I marry pasta and sauce: I transfer pasta to the skillet, add Parmesan by the handful, and toss vigorously, adding more pasta water as needed until the sauce turns glossy and clings.

9. I finish to taste: I add lemon zest and a squeeze of juice, black pepper, herbs, and, if I’m craving extra richness, a spoonful of mascarpone or a tiny splash of cream.

10. I serve immediately with extra Parmesan.

Servings and timing

I get 4 generous servings. I spend about 10 minutes slicing, 35–45 minutes caramelizing and building the sauce, and 8–10 minutes cooking pasta—about 55–65 minutes total.

Variations

• French-onion style: I swap part of the wine for beef stock and finish with a blend of Gruyère and Parmesan.

• Mushroom umami: I sauté sliced cremini or shiitakes after the onions caramelize, then deglaze.

• Bacon or pancetta: I crisp 100 g diced pancetta first, cook the onions in the fat (plus a touch of oil), and sprinkle the crispy bits on top.

• Vegan: I skip butter and cheese, use olive oil only, miso for umami, and finish with a knob of vegan butter for sheen.

• Spicy Calabrian: I fold in a teaspoon of Calabrian chili paste with the garlic for a gentle burn.

• Creamier: I stir in 2–3 tablespoons mascarpone at the end for a velvet finish.

storage/reheating

I refrigerate leftovers in an airtight container for up to 4 days. For best texture, I reheat in a skillet over medium heat with a splash of water or stock, tossing until the sauce loosens and turns glossy again. I avoid the microwave if I can—it can make the pasta gummy. The caramelized onions themselves freeze beautifully up to 3 months; I thaw and use them to make a fresh batch fast.

FAQs

How do I caramelize onions faster without burning them?

I keep the heat at medium-low and add a teaspoon or two of water whenever the pan looks dry. If I’m in a rush, I add a tiny pinch (⅛ teaspoon) of baking soda to jump-start browning, stirring constantly and watching closely.

Why did my onions turn bitter?

I likely used heat that was too high or didn’t deglaze often enough. I fix it with a splash of water or stock to dissolve any scorched bits, then add a touch of vinegar and a pinch of sugar to rebalance.

Which onions work best?

I reach for yellow onions for balanced sweetness and savoriness. Sweet onions caramelize nicely but can end up one-note; I add an extra pinch of salt and a splash of vinegar when using them.

Do I need wine?

I don’t; stock or even water works. I still add a small splash of vinegar or lemon to bring back the brightness that wine would have provided.

How do I get that glossy, clingy sauce?

I toss the pasta with the onions over heat, adding starchy pasta water in small additions and showering in cheese while I toss. The starch and fat emulsify into a silky coating.

Conclusion

I let onions take the lead—slowly caramelized until sweet and savory—then I build a simple pan sauce that hugs every strand. With a few smart splashes and a handful of cheese, I turn pantry staples into a deeply comforting pasta that tastes far more luxurious than the ingredient list suggests.