Caramelized Onion Pasta Chili

This caramelized onion pasta with chilli oil transforms humble ingredients into a restaurant-worthy dish that balances sweet, savory, and spicy flavors. The slow-cooked onions develop a rich sweetness that pairs perfectly with the punchy heat of homemade chilli oil, creating a pasta that's both comforting and exciting.

I first made this pasta during a particularly cold winter evening when I was craving something comforting yet bold. The aroma of slowly caramelizing onions filled my kitchen, and since that night, it has become my go-to impressive dinner when friends come over.

Ingredients

• 12 oz pasta of your choice: The shape matters less than quality here. Use bronze-die extruded pasta if possible for better sauce adhesion
• 2 large onions, thinly sliced: Yellow or sweet onions work best as they caramelize beautifully with natural sugars
• 2 tablespoons olive oil: Use a good-quality oil as it forms the base of the flavor
• 1 tablespoon butter: Adds richness and helps prevent the onions from burning
• 1 teaspoon sugar: Optional but helps achieve deeper caramelization faster
• 1/4 cup olive oil for chilli oil: Choose a fruity variety rather than a bitter one
• 1 tablespoon chilli flakes: Adjust based on your heat preference. Korean gochugaru works wonderfully too
• 1 garlic clove: Fresh is essential here for the most vibrant flavor
• 1/2 teaspoon smoked paprika: Adds a subtle smoky depth that elevates the entire dish
• Fresh parsley and Parmesan: These finish the dish with freshness and umami

Step-by-Step Instructions

Start the Caramelization:

Heat olive oil and butter in a large skillet over medium-low heat until butter melts completely. Add your thinly sliced onions with a generous pinch of salt, spreading them evenly across the pan. The salt helps draw out moisture and begins the caramelization process.

Practice Patience:

This is the most crucial step. Cook the onions for a full 25-30 minutes, stirring only occasionally about every 3-4 minutes. The onions will gradually transform from white to translucent, then golden, and finally to a deep amber brown. If they start sticking, add a tablespoon of water rather than more oil.

Make the Chilli Oil:

While the onions cook, prepare your chilli oil. Heat 1/4 cup olive oil in a small saucepan over medium-low heat. Once warm but not smoking, add the minced garlic and chilli flakes. Cook for exactly 90 seconds, stirring constantly to infuse the oil without burning the garlic. Add the smoked paprika and salt, stir thoroughly, then immediately remove from heat.

Cook the Pasta:

Bring a large pot of water to a rolling boil. Add enough salt to make it taste like seawater about 1 tablespoon per quart. Cook the pasta about 1 minute less than package directions for perfect al dente texture. Before draining, scoop out 1/2 cup of starchy pasta water.

Create the Final Dish:

Return the caramelized onions to medium heat if they've cooled. Add the drained pasta directly to the onion pan along with about 1/4 cup of the reserved pasta water. Toss continuously for 1-2 minutes until the pasta absorbs some of the onion flavor and the starches create a light sauce. Drizzle three-quarters of the chilli oil over everything and toss again to coat every strand.

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My absolute favorite part of this recipe is that magical moment when the onions hit peak caramelization after about 25 minutes cooking. The kitchen fills with an incredible sweet aroma that signals dinner is about to be extraordinary. I've found that using a heavy-bottomed pan makes a noticeable difference in how evenly the onions caramelize.

Make-Ahead Options

The caramelized onions can be prepared up to three days in advance and stored in an airtight container in the refrigerator. This makes weeknight preparation significantly faster since the most time-consuming step is already done. The chilli oil can also be made ahead it actually improves after sitting for 24 hours as the flavors fully infuse. Store it at room temperature in a sealed glass container for up to two weeks, and you'll have it ready for this pasta or to drizzle over eggs, pizza, or vegetables.

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Perfect Pairings

This pasta works beautifully as a main dish accompanied by a simple arugula salad dressed with lemon juice and olive oil. The peppery greens and bright acidity perfectly cut through the richness of the caramelized onions. For wine lovers, a medium-bodied red with good acidity like a Sangiovese or Barbera complements the sweetness of the onions while standing up to the chilli heat. If you prefer white wine, a dry but aromatic Vermentino offers enough body without overwhelming the dish.

Variations Worth Trying

Transform this pasta into a heartier meal by adding protein. Crispy pancetta or bacon bits folded in at the end add a wonderful savory crunch. For a vegetarian protein boost, add a can of drained white beans when tossing the pasta with the onions. The beans warm through and absorb the flavors while adding creamy texture. Another delicious variation is adding 1/2 cup of crumbled goat cheese right before serving it melts slightly from the heat, creating pockets of tangy creaminess throughout the dish.

Frequently Asked Questions

→ How do you caramelize onions perfectly?

Cook thinly sliced onions on medium-low heat with olive oil and butter, stirring occasionally for 25-30 minutes until golden-brown.

→ How spicy is the chili oil?

The spice level can be adjusted by increasing or decreasing the chili flakes and smoked paprika. It's customizable to your preference.

→ Can I make caramelized onions in advance?

Yes, caramelized onions can be made ahead of time and stored in the refrigerator for up to 2-3 days in an airtight container.

→ What type of pasta works best for this dish?

Spaghetti, fettuccine, or penne work well, but you can use any pasta of your choice for this recipe.

→ Can I add other ingredients to this dish?

Absolutely! Roasted vegetables like zucchini or bell peppers can add texture and flavor to the pasta.