Introduction

This Caramelized Onion Pasta with Chilli Oil is a simple yet flavorful dish that balances sweet, savory, and spicy notes perfectly. With tender, golden onions and a kick of homemade chili oil, it’s an easy recipe that elevates your weeknight dinner.

A close-up view of a bowl filled with creamy spaghetti pasta arranged in a swirl, topped with dark brown crispy garlic pieces and finely chopped green parsley leaves scattered over the top. There are small flakes of red chili pepper and a light dusting of grated cheese over the glossy noodles, which have a slightly oily shine. The bowl is white with a dark gray inside, placed on a white marbled surface, highlighting the warm colors of the pasta and toppings. Photo taken with an iphone --ar 4:5 --v 7

Ingredients

12 oz (340g) pasta of your choice (spaghetti, fettuccine, or penne works well)
Salt (for boiling pasta water)
2 large onions, thinly sliced
2 tablespoons olive oil
1 tablespoon butter
1 teaspoon sugar (optional, to help caramelize)
Salt and pepper, to taste
1/4 cup olive oil
1 tablespoon chili flakes (adjust based on preferred spice level)
1 garlic clove, minced
1/2 teaspoon smoked paprika (optional)
1/2 teaspoon salt
Fresh parsley, chopped (optional)
Grated Parmesan cheese (optional)
Extra chili oil (optional)

Instructions

Step 1: In a large skillet, heat 2 tablespoons olive oil and 1 tablespoon butter over medium-low heat. Add the thinly sliced onions and a pinch of salt, stirring occasionally to cook evenly.
Step 2: Sprinkle 1 teaspoon sugar over the onions if using, and continue to cook for 25-30 minutes, stirring occasionally, until the onions turn deep golden-brown and caramelized. Set aside.
Step 3: In a small saucepan, heat 1/4 cup olive oil over low to medium heat. Add minced garlic and chili flakes, stirring occasionally for 1-2 minutes to infuse the oil without burning the garlic.
Step 4: Stir in smoked paprika and 1/2 teaspoon salt if using. Remove from heat and set aside to cool.
Step 5: Bring a large pot of salted water to a boil. Cook the pasta according to package instructions until al dente, about 8-10 minutes. Drain, reserving about 1/2 cup of pasta cooking water.
Step 6: Return the skillet with caramelized onions to low heat. Add the cooked pasta and toss to combine, adding reserved pasta water as needed to help coat the pasta evenly.
Step 7: Pour the prepared chili oil over the pasta and toss again until well coated with the spicy oil.
Step 8: Serve immediately, garnished with chopped parsley and grated Parmesan cheese if desired. Drizzle with extra chili oil for additional heat.

Tips & Variations

Use a mix of sweet and yellow onions for a deeper caramelized flavor.
Adjust chili flakes to control the spice level; start with less and add more to taste.
For a vegan version, omit butter and Parmesan cheese, or substitute with vegan alternatives.
Adding a squeeze of lemon juice before serving can brighten the flavors.

Storage

Store leftover pasta in an airtight container in the refrigerator for up to 3 days. Reheat gently in a skillet over low heat, adding a splash of water or olive oil to prevent sticking. The chili oil flavor may intensify upon reheating.

How to Serve

A close-up view of a dish of spaghetti neatly twirled into a small mound on a white bowl. The pasta is coated in a shiny, light brown sauce with visible bits of garlic and chili flakes, giving it a slightly oily texture. Scattered on top and throughout the spaghetti are small pieces of dark red dried chili and a sprinkling of finely chopped green herbs, adding color contrast. The bowl is set on a white marbled surface, highlighting the warm tones of the pasta. photo taken with an iphone --ar 4:5 --v 7

Serve this delicious recipe with your favorite sides.

FAQs

Can I use pre-made chili oil instead of making it from scratch?

Yes, pre-made chili oil works well as a convenient shortcut, though making your own allows you to control the spice level and flavor intensity.

What type of pasta works best for this dish?

Spaghetti, fettuccine, or penne are all excellent choices as they hold the caramelized onions and chili oil nicely, but feel free to use your favorite pasta shape.