Caramelized Onion and Garlic Spaghetti – Easy Vegetarian Pasta Recipe

Why You’ll Love This Recipe

I enjoy this recipe because it’s cozy, satisfying, and surprisingly elegant for how simple it is. It’s perfect for weeknight dinners when I want something hearty without feeling heavy. I also like how flexible it is, whether I keep it minimal or dress it up with herbs, cheese, or greens.

Ingredients

(Here’s a tip: Check out the full list of ingredients and measurements in the recipe card below.)

12 oz spaghetti (or linguine or fettuccine)
3 large onions, thinly sliced
4 garlic cloves, minced
3 tbsp olive oil or butter
1/2 cup reserved pasta water
1/4 cup grated Parmesan (optional)
1 tbsp fresh parsley, chopped
Pinch of chili flakes (optional)
Salt and pepper, to taste

Directions

I start by heating the olive oil in a large skillet over low heat. I add the sliced onions and cook them slowly, stirring occasionally, for about 30 to 40 minutes until they turn golden, soft, and deeply caramelized. I find that patience here really brings out their natural sweetness.

Once the onions are jammy and fragrant, I stir in the minced garlic and cook it briefly until just golden and aromatic, being careful not to let it burn.

While the onions cook, I boil the spaghetti in well-salted water until al dente. Before draining, I reserve about 1/2 cup of the pasta water, then drain the pasta.

I add the cooked pasta directly to the skillet with the onions and garlic. I pour in some of the reserved pasta water and toss everything together until the sauce becomes silky and coats the noodles evenly.

I season with salt, pepper, and chili flakes if I’m using them. I finish the dish with grated Parmesan and fresh parsley before serving.

Servings and Timing

I get about 4 servings from this recipe.
Prep time is approximately 10 minutes.
Cook time is about 40 minutes.
Total time comes to roughly 50 minutes.

Variations

I sometimes add spinach or kale at the end for freshness and color. When I want a richer flavor, I finish the pasta with a knob of butter. For a vegan version, I skip the Parmesan and use nutritional yeast instead.

Storage/Reheating

I store leftovers in an airtight container in the refrigerator for up to 3 days. When reheating, I warm the pasta gently on the stovetop with a splash of water or olive oil to bring the sauce back together.

FAQs

Why do the onions take so long to cook?

I cook them low and slow so their natural sugars caramelize fully and develop deep flavor.

Can I use a different type of pasta?

I’ve used linguine, fettuccine, and even short pasta shapes with great results.

Is this dish spicy?

I find it mild, but I adjust the chili flakes depending on how much heat I want.

Do I really need the pasta water?

I always use it because it helps create a smooth, glossy sauce that binds everything together.

Can I make this vegan?

I simply skip the cheese or replace it with nutritional yeast, and it works beautifully.

Conclusion

I find this caramelized onion and garlic spaghetti to be the definition of simple comfort food done right. It’s rich, cozy, and full of flavor, making it a dish I return to whenever I want something satisfying, vegetarian, and effortlessly delicious.

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