Caramelized Onion Pasta

All you need for this caramelized onion pasta recipe is a bag of onions, a few cloves of garlic, some dried pasta, and a wedge of cheese. Slowly cooking the sliced onions in butter and olive oil coaxes out their natural sugars, turning them deeply golden, sweet, and almost jammy. Pasta water and finely grated Parmesan do double duty here, adding seasoning and structure as they emulsify into a silky cream-free sauce. Finished with a squeeze of lemon and fresh parsley, this easy vegetarian pasta is proof that a luxurious dinner can come from the most basic pantry ingredients.

Tips and FAQs for the best caramelized onion pasta

• How long does it take to caramelize onions?
  True caramelized onions take at least 30 minutes over medium heat. Stir occasionally and resist the urge to rush—low, steady heat is key to developing deep flavor without burning.
• What type of onions work best?
  Sweet onions (Vidalia, Maui, Walla Walla) or yellow onions are the best for caramelized onion pasta because they soften evenly and develop a balanced sweetness. White onions and red onions will work in a pinch, but their flavor will be sharper.
• What’s the best pasta shape for this recipe?
  Long strands like linguine, spaghetti, or fettuccine work best, as they hold onto the silky onion-Parmesan sauce. More about pairing pasta shape to sauce this way →
• How can I customize this dish?
  Add red pepper flakes for heat, thyme or sage for earthiness, or crispy breadcrumbs for texture. Toss in some sautéed mushrooms or, for protein, top with a poached egg.
• Why reserve so much pasta water?
  Having extra pasta water lets you loosen the sauce gradually and achieve a glossy consistency without breaking the creamy (but cream-less) emulsion. You may not need all of it, but as the saying goes, it’s better to have too much than not enough.