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This Caramelized Onion Pasta with Chilli Oil packs layers of sweet and savory flavor with just the right kick of heat. By slow-cooking onions until deep golden and finishing the dish with homemade chili oil, you transform a straightforward bowl of pasta into a restaurant-worthy meal. It is a versatile and memorable dinner that takes humble ingredients and turns them into something spectacular.
My first attempt at this dish happened on a busy evening when I raided the pantry with little hope. Now I turn to it every time I want to impress guests or need a comforting meal in a pinch.
Ingredients
- Pasta: Use your favorite shape like spaghetti or penne as it holds the sauce and onions well. Choose quality pasta made with semolina for the best bite
- Large onions: Go for yellow or sweet onions since they caramelize beautifully and add intense flavor
- Olive oil: Extra virgin for both cooking and chili oil to enhance the richness and fragrance
- Butter: A touch in the onions brings richness and helps them brown evenly
- Sugar: Optional but a little speeds up browning and deepens the sweetness
- Salt and pepper: For seasoning the onions and pasta water use flaky salt for boiling pasta
- Chili flakes: Use your preferred level of heat and seek fresh flakes for the most vibrant color and taste
- Garlic: Fresh cloves add an aromatic backbone to the chili oil do not use pre-minced for best results
- Smoked paprika: Optional but adds a subtle smokiness that complements both onion and chili
- Fresh parsley: For garnish adds freshness and color use flat-leaf for better flavor
- Parmesan cheese: Freshly grated on top gives a creamy finish and a salty boost
Instructions
- Caramelize the Onions:
- In a wide skillet melt olive oil and butter over medium-low heat. Add sliced onions and a good pinch of salt. Stir regularly to prevent sticking. After ten minutes sprinkle in the sugar if using and keep cooking for another twenty to twenty-five minutes. The onions should turn deep golden and reduce in volume making your kitchen smell incredible. Set aside once complete
- Infuse the Chilli Oil:
- While the onions cook pour olive oil in a small pan and put it on low heat. Add minced garlic and chili flakes. Cook just until the garlic is fragrant about one to two minutes but do not let it brown. Add the smoked paprika and salt gently stir and set aside to infuse
- Boil the Pasta:
- Bring a large pot of salted water to a rolling boil. Drop in your pasta and cook until perfectly al dente usually eight to ten minutes. Taste a noodle at the minimum cook time to check for chew. Reserve half a cup of pasta water before draining
- Combine Onions and Pasta:
- With the pasta drained add it into the pan with caramelized onions. Toss everything so the onions coat the noodles. Splash in reserved pasta water to help the sauce cling to each strand and avoid sticking
- Finish with Chilli Oil:
- Drizzle the garlic chili oil over the pasta while still hot. Toss again to fully coat each piece. Adjust with extra pasta water if needed so the pasta is glossy not dry
- Garnish and Serve:
- Top each plate with chopped parsley and fresh grated Parmesan. Drizzle with more chili oil if you love the heat and serve immediately when the aroma is at its peak
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The chillies I use are always from a local Italian grocer who told me to try them in my oil it was a total game changer. My favorite onions are the sweet kind because they caramelize faster and bring an almost jammy flavor to the pasta. My niece tried this recipe with her friends and they all texted the next day for the step-by-step because it turned their pasta night into something totally new.
Storage Hints
Store leftover caramelized onions and chili oil separately in air-tight containers in the fridge for up to three days. Reheat the onions slowly in a pan and gently warm the oil before using. If you are storing leftover pasta add a splash of water before reheating.
Ingredient Swaps
Gluten free pasta works great and holds up well to the rich sauce. If you want less heat choose Aleppo pepper or sweet paprika. Vegan butter or just more olive oil will keep the recipe dairy free with almost the same rich taste.
Serving Ideas
This dish stands alone but pairs beautifully with simple roasted vegetables or a crisp salad. It is a showstopper for dinner parties served in big shallow bowls with extra Parmesan on the table and garlic bread on the side.
A Bit of Context
Caramelized onions are a classic staple across many cuisines from French onion soup to Indian curries. Pairing them with pasta is a tradition that started in my own kitchen but is inspired by Italian aglio e olio with an oniony twist. The chili oil brings a touch of Asia and the Mediterranean and punches up the flavor of basic pasta.
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For the best results let your onions take their time to caramelize. This dish delivers comfort and a restaurant-quality feel any night of the week.
Frequently Asked Questions
- → How do I achieve perfectly caramelized onions?
Cook thinly sliced onions over medium-low heat with olive oil and butter, stirring occasionally for 25-30 minutes until they're deeply golden and sweet.
- → Can I adjust the spiciness of the chilli oil?
Yes, simply vary the amount of chili flakes based on your heat preference or add extra oil to mellow the spice.
- → What pasta shapes work best?
Spaghetti, fettuccine, or penne all soak up the flavors well, but feel free to use any preferred pasta variety.
- → Is it possible to prepare the onions in advance?
Absolutely. Caramelized onions can be made ahead and refrigerated for up to three days, streamlining prep.
- → Are there suggested garnishes for extra flavor?
Fresh parsley, grated Parmesan, and an extra drizzle of chili oil make wonderful final touches.