What the heck is this?

This isn’t your average weeknight pasta. We’re talking slow-cooked, golden-brown onions that turn sweet and savory at the same time, twirled into perfectly cooked noodles and finished with a spicy, garlicky chili oil drizzle. It’s one of those “how is this so simple and yet so dang good?” recipes. Minimal ingredients, maximum flavor. Oh—and it’s totally vegetarian.

Why You’ll Love This Recipe

Because it’s silky. It’s spicy. It’s got layers of flavor from the slow caramelized onions and that punchy chili oil. You don’t need a ton of stuff to make it, and it feels fancy without the effort. Great for a cozy dinner, a date night in, or any time you want pasta with attitude.

The Good Stuff You’ll Need

For the pasta
12 oz spaghetti, fettuccine, or your fave long pasta
3 large yellow onions, thinly sliced
2 tbsp olive oil or butter
Salt, to taste
½ cup pasta water (save it!)
Parmesan or Pecorino, for serving (optional but excellent)

For the chili oil
¼ cup olive oil
3 garlic cloves, thinly sliced
1 tsp red pepper flakes (or more, if you’re bold)
½ tsp smoked paprika (adds depth)
Salt, to taste

Let’s Do This

Step 1: Caramelize the Onions
In a large skillet over medium-low heat, add olive oil (or butter) and sliced onions. Cook low and slow—about 30–40 minutes—stirring every so often until they’re deeply golden, sweet, and jammy. Add a pinch of salt partway through. Yes, it’s worth the wait.

Step 2: Boil the Pasta
While the onions do their thing, cook your pasta in salted boiling water until al dente. Before draining, scoop out about ½ cup of the starchy pasta water and save it for later.

Step 3: Make the Chili Oil
In a small saucepan, heat olive oil over medium-low heat. Add garlic and cook until it’s just starting to turn golden. Then add red pepper flakes, paprika, and a pinch of salt. Let it sizzle for 30 seconds, then take it off the heat so nothing burns.

Step 4: Bring It All Together
Add your drained pasta to the skillet with the caramelized onions. Pour in some of the reserved pasta water and toss it all together until the noodles are glossy and coated. Drizzle with your homemade chili oil and give it another toss. Taste for salt. Want more heat? Add more chili oil.

Step 5: Serve It Up
Plate that beauty, sprinkle with grated Parmesan or Pecorino if you like, and maybe top with some chopped fresh herbs (parsley, basil, or chives are all great). Serve hot—and definitely don’t skip a final drizzle of chili oil over the top.

Serving Suggestions

Serve with a crisp green salad or roasted veggies for a complete meal. Garlic bread wouldn’t hurt either. For wine: a dry white or a light red like Pinot Noir plays really well with the sweet-spicy combo.

Switch It Up

Add spinach or kale at the end for a pop of green
Stir in roasted cherry tomatoes or sun-dried tomatoes for extra depth
Toss in crispy breadcrumbs for crunch
Use shallots instead of onions for a more delicate flavor

Make-Ahead Tips

You can caramelize the onions and make the chili oil ahead of time. Store both in the fridge for up to 3 days. When ready to eat, reheat, boil pasta fresh, toss together, and done.

Questions People Actually Ask

Q: Can I use store-bought chili oil?
A: Totally! Just make sure it’s good quality and not too overpowering. Homemade does give you control over the spice and flavor.

Q: What pasta works best?
A: Long noodles like spaghetti or linguine are perfect for catching the silky onion strands and chili oil, but short pasta like rigatoni works too!

Q: How do I store leftovers?
A: Pop them in an airtight container in the fridge. Reheat gently with a splash of water or extra oil so it stays saucy.

Q: Is this vegan?
A: Yep—as long as you skip the cheese or use a plant-based version. Everything else is already plant-powered.

Caramelized Onion Pasta

Author: Tyla
Total Time: 9 minute
Yield: 4 servings

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