Easy Caramelized Onion Pasta
Sweet, slow-cooked onions melt into a silky sauce that clings to twirls of pasta. A splash of balsamic and Parmesan brings everything together fast.
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Servings:
Ingredients
Main Ingredients
- 2 tbsp olive oil
- 3 tbsp unsalted butter
- 2 lb yellow onions, thinly sliced
- 1.25 tsp kosher salt
- 0.5 tsp black pepper
- 0.25 tsp red pepper flakes optional
- 1.5 tsp minced garlic
- 1 tsp chopped fresh thyme
- 1.5 tbsp balsamic vinegar
- 12 oz dried spaghetti
- 1 cup reserved pasta water from cooking the pasta
- 0.75 cup grated Parmesan cheese
- 2 tbsp chopped fresh parsley for garnish
Instructions
Preparation Steps
- Warm a wide skillet over medium-low heat. Add olive oil and 2 tbsp butter.
- Add sliced onions and about 1 tsp salt. Cook slowly, stirring often, until deep golden, 25–35 minutes.
- Stir in garlic, thyme, and red pepper flakes. Cook 1 minute until fragrant.
- Pour in balsamic vinegar and scrape up browned bits. Simmer 2 minutes until glossy, then keep warm on low.
- Boil spaghetti in salted water until al dente. Reserve 1 cup cooking water, then drain.
- Add pasta to the onions with a splash of pasta water and remaining 1 tbsp butter. Toss to coat.
- Sprinkle in Parmesan, tossing and adding more pasta water as needed until saucy and silky.
- Season with remaining salt and the black pepper. Finish with parsley and serve hot.
Notes
Variation ideas: Swap Parmesan for Pecorino Romano for a sharper bite, or add a splash of dry white wine with the vinegar. Stir in crisp pancetta or sautéed mushrooms for extra richness. Leftovers keep 3 days in the fridge; reheat gently with a spoonful of water to loosen the sauce.
This recipe is an original creation inspired by classic Easy Caramelized Onion Pasta flavors. All ingredient ratios and instructions are independently developed.