Name: Caramelized Onion Pasta with Chilli Oil
Prep time: 10 min
Cook time: 40 min
Total time: 50 min
Cuisine: Italian-inspired
Ingredients: 3 large yellow onions; 2 tablespoons butter; 1 tablespoon olive oil; 3 cloves garlic, minced; 12 ounces spaghetti; 1 cup grated Parmesan cheese; Salt, to taste; Black pepper, to taste; 1 cup reserved pasta water; 2 tablespoons chilli oil (or to taste); 1 teaspoon fresh thyme leaves (optional)

Rich, creamy, and absolutely unforgettable—this Caramelized Onion Pasta with Chilli Oil is the kind of dish that surprises you with its depth of flavor. Sweet, slowly-cooked onions are the heart of this pasta, blending into a silky sauce that clings to every strand of spaghetti. And just when you think it’s all comfort and warmth, the homemade chilli oil kicks in with a bold, fiery edge that brings it all to life.

Whether you’re cooking for a cozy date night or just want to spoil yourself with something special on a weekday evening, this pasta delivers. It feels fancy without requiring too much effort, and it’s packed with umami, sweetness, spice, and a touch of smokiness that’s just irresistible.

Why You’ll Love This Caramelized Onion Pasta with Chilli Oil

This pasta is a lesson in how a few simple ingredients can transform into something magical. The slow caramelization of the onions develops a deep, sweet-savory flavor that becomes the base of a creamy, almost luxurious sauce. Add to that a generous drizzle of spicy chilli oil, and you’ve got a showstopper of a dish.

It’s vegetarian, made with pantry staples, and totally customizable. Plus, it comes together in under an hour and can easily impress dinner guests or satisfy your craving for something rich and spicy.

What Kind of Pasta Should I Use?

Spaghetti or bucatini works beautifully here because the sauce clings to the long strands, creating a perfect bite every time. But honestly, don’t stress—any pasta you love will do the job. Linguine, fettuccine, or even rigatoni can stand in. Just be sure to cook it al dente and save some of that pasta water to help marry the sauce with the noodles seamlessly.

Ingredients for the Caramelized Onion Pasta with Chilli Oil

Each ingredient in this dish plays a crucial role in delivering that bold and comforting flavor:

Yellow onions: The star of the dish. Slow-cooked until golden and jammy, they form the flavorful base of the sauce.
Butter and olive oil: A perfect combo for caramelizing onions to a rich, glossy finish.
Garlic: Adds an aromatic punch that deepens the flavor.
Spaghetti: Long, twirl-able noodles that soak up the sauce beautifully.
Parmesan cheese: Adds a salty, creamy finish that binds the dish together.
Salt & black pepper: Essential for balancing sweetness and enhancing flavors.
Pasta water: Helps emulsify the sauce, making it cling to the pasta.
Chilli flakes or homemade chilli oil: Brings the heat and cuts through the richness.
Fresh thyme (optional): For a burst of earthiness and color on top.

Caramelized Onion Pasta with Chilli Oil - Pin 1

How To Make the Caramelized Onion Pasta with Chilli Oil

Step 1: Caramelize the Onions

Slice 3 large yellow onions thinly. Heat butter and olive oil in a large skillet over medium-low heat. Add the onions and a pinch of salt, and cook slowly, stirring occasionally, for about 35-40 minutes until deeply golden and jammy.

Step 2: Cook the Pasta

Boil salted water and cook your spaghetti until al dente. Reserve 1 cup of pasta water before draining.

Step 3: Build the Sauce

Once the onions are caramelized, add minced garlic and cook for another minute. Then, stir in about 1/2 cup of the pasta water and let it simmer. Toss in the cooked pasta and grated Parmesan cheese, stirring until creamy. Add more pasta water if needed to loosen the sauce.

Step 4: Add the Heat

Drizzle chilli oil or sprinkle red pepper flakes over the pasta and toss gently. Adjust the spice to your preference.

Step 5: Serve and Garnish

Plate the pasta, top with fresh thyme and a little more chilli oil if desired. Serve immediately while hot and glossy.

Serving and Storing This Caramelized Onion Pasta with Chilli Oil

This rich and savory pasta serves about 4 people, making it perfect for a cozy family dinner or a small gathering. Serve it straight off the stove for the best creamy texture and bold flavor.

If you have leftovers, store them in an airtight container in the fridge for up to 3 days. Reheat gently on the stove with a splash of water or broth to loosen the sauce. The flavors often deepen overnight, making leftovers just as delicious.

What to Serve With Caramelized Onion Pasta with Chilli Oil

Garlic Bread

A crunchy, buttery side that pairs perfectly with the creamy richness of the pasta.

Simple Arugula Salad

Peppery arugula with a light lemon vinaigrette provides a fresh, tangy contrast.

Roasted Broccoli

The slightly charred edges and earthy flavor of roasted broccoli are a great match.

Grilled Chicken

If you’re looking to add protein, grilled or roasted chicken works beautifully without overpowering the dish.

Burrata

Creamy burrata adds a touch of luxury and balances the spice with cool creaminess.

Sauteed Mushrooms

Earthy and savory, mushrooms are a natural complement to the caramelized onions.

White Wine

A crisp white wine like Pinot Grigio or Sauvignon Blanc enhances the dish without competing with the spice.

Frequently Asked Questions

Can I make this pasta vegan?
Absolutely. Just swap out the butter for vegan butter and use nutritional yeast or a vegan Parmesan substitute to get that umami depth.

How spicy is the chilli oil?
That depends on how much you use. The heat level is completely customizable—start with a drizzle and add more to taste.

Can I use pre-made caramelized onions?
If you’re in a pinch, yes—but fresh homemade caramelized onions will always bring better flavor and texture.

Is this pasta good for meal prep?
Yes! The pasta stores well and reheats beautifully. It’s great for lunches or a quick dinner the next day.

What can I use instead of Parmesan?
Pecorino Romano or Grana Padano are excellent substitutes. For dairy-free, try a nut-based cheese or nutritional yeast.

Save This Pin For Later

📌 Save this recipe to your Pinterest dinner board so you can come back to it any time.
And let me know in the comments how yours turned out. Did you go heavy on the chilli oil, or keep it mellow? Add any herbs?

I love hearing how others make these recipes their own. Questions are welcome too, let’s help each other cook smarter.

For more bold and cozy recipes like this one, check out my Life With Livia Pinterest for daily inspiration.

Conclusion

Caramelized Onion Pasta with Chilli Oil is comfort food with a fiery twist. It brings together deep, sweet caramelized onions with a bold chilli oil kick that transforms a humble pasta night into something extraordinary. It’s easy to make, endlessly adaptable, and guaranteed to become a go-to favorite in your kitchen.

Caramelized Onion Pasta with Chilli Oil

Author: Livia Scott
Total Time: 50 minutes
Yield: 4 servings
Diet: Vegetarian

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Description

This Caramelized Onion Pasta with Chilli Oil is a rich, spicy, and satisfying dish perfect for a cozy dinner or a quick yet elevated weeknight meal. Made with sweet, jammy caramelized onions, twirlable spaghetti, and a bold drizzle of chilli oil, it’s the kind of recipe that turns simple pantry ingredients into something extraordinary. Whether you’re looking for easy dinner ideas, comfort food with a twist, or a vegetarian pasta recipe with bold flavor, this one checks all the boxes. It also fits perfectly into your list of quick dinners and weeknight meal plans.