Creamy Caramelised Onion Spaghetti

Creamy Caramelised Onion Spaghetti is a rich, creamy, slightly sweet, spicy, and savory pasta dish packed with deep umami flavor. Slowly caramelised onions are combined with garlic, chili oil, soy sauce, cream, and pasta water to create a smooth sauce that coats every strand of spaghetti.

Why You’ll Love This Recipe

• Rich, creamy, and full of flavor
• Sweet and savory caramelised onions
• A delicious spicy kick from chili oil and chili flakes
• Simple ingredients
• Perfect for a comforting lunch or dinner
• Easy to customize with your favorite cheese and seasonings

Recipe Information

• Prep Time: 10 minutes
• Cook Time: 30–40 minutes
• Total Time: 40–50 minutes
• Servings: 2–3
• Course: Main Course
• Cuisine: Italian-Inspired

Ingredients

• Spaghetti, about 200–250 g
• Butter and oil, for cooking
• 3 large onions, thinly sliced into half-moons
• 2–3 cloves garlic, minced
• 1 tablespoon chili oil, or more to taste
• 2 tablespoons soy sauce
• ¾ cup heavy cream
• About 1 cup reserved pasta water
• 1 teaspoon dried oregano
• ½–1 teaspoon chili flakes, to taste
• Salt and black pepper, to taste
• ½ teaspoon garlic powder
• 1 teaspoon dried garlic flakes, optional
• Fresh basil, chopped
• Mozzarella or grated Parmesan, for topping
• Extra chili oil, for finishing

Instructions

1. Cook the Spaghetti

Bring a large pot of salted water to a boil. Cook the spaghetti according to the package instructions until al dente.

Before draining, reserve about 1 cup of the pasta water. Drain the spaghetti and set it aside.

2. Caramelise the Onions

Heat a large skillet over low to medium-low heat. Add a little butter and oil, then add the sliced onions.

Cook the onions slowly, stirring occasionally, until they become very soft, golden brown, and deeply caramelised. This can take about 25–35 minutes depending on the heat and the amount of browning you prefer.

If the onions begin to stick or brown too quickly, reduce the heat and add a small splash of water.

3. Add the Garlic and Seasonings

Add the minced garlic to the caramelised onions and cook for about 30–60 seconds until fragrant.

Add the chili oil, soy sauce, oregano, chili flakes, garlic powder, garlic flakes, and a little black pepper. Stir well to combine.

4. Make the Creamy Sauce

Pour in the heavy cream and stir until combined with the onions and seasonings.

Gradually add some of the reserved pasta water, stirring as you go, until the sauce reaches a smooth and creamy consistency.

5. Add the Spaghetti

Add the cooked spaghetti to the skillet and toss thoroughly to coat the pasta in the creamy onion sauce.

Cook over low heat for 1–2 minutes, adding more pasta water if necessary, until the sauce becomes glossy and coats the spaghetti evenly.

6. Garnish and Serve

Remove the skillet from the heat and stir in some chopped fresh basil.

Serve immediately with plenty of mozzarella or freshly grated Parmesan. Finish with an extra drizzle of chili oil and a sprinkle of chili flakes if desired.

Recipe Tips

• Cook the onions slowly over low heat for the best caramelised flavor.
• Do not rush the caramelisation process by using high heat, as the onions can burn before becoming properly caramelised.
• Reserve pasta water before draining because its starch helps create a smooth, creamy sauce.
• Add the pasta water gradually rather than all at once to control the sauce consistency.
• Soy sauce adds umami and salt, so taste the sauce before adding extra salt.
• Add chili oil gradually if you prefer a milder pasta.
• Serve immediately for the best creamy texture.

Variations

You can customize this creamy caramelised onion spaghetti with your favorite ingredients.

• Mushrooms
• Spinach
• Roasted red peppers
• Sun-dried tomatoes
• Cooked chicken
• Crispy bacon
• Red pepper flakes
• Fresh parsley
• Extra Parmesan cheese

Serving Suggestions

Serve the spaghetti hot with a fresh green salad, roasted vegetables, garlic bread, or a simple side of steamed vegetables.

Storage

Refrigerator

Allow leftovers to cool, then transfer them to an airtight container. Refrigerate and consume within 3 days.

Reheating

Reheat gently in a skillet over low to medium heat. Add a small splash of water, milk, or cream while reheating to loosen the sauce and restore its creamy consistency.

Nutrition

Nutritional values will vary depending on the amount of butter, oil, cream, cheese, and spaghetti used.

For the most accurate nutritional information, calculate the recipe using the exact ingredients and brands used.

Frequently Asked Questions

How long should I caramelise the onions?

For deeply caramelised onions, allow approximately 25–35 minutes over low to medium-low heat. The exact time depends on the amount of onions, pan, and heat level.

Can I use milk instead of heavy cream?

Yes, but the sauce will be lighter and less rich. Heavy cream provides a thicker and creamier texture.

Can I make this pasta less spicy?

Yes. Reduce or omit the chili oil and chili flakes to suit your preferred spice level.

Can I use Parmesan instead of mozzarella?

Absolutely. Parmesan adds a salty, nutty flavor, while mozzarella provides a softer and cheesier finish. You can also use a combination of both.

Can I use another type of pasta?

Yes. Linguine, fettuccine, bucatini, or penne can all work well with this creamy caramelised onion sauce.

Final Thoughts

Creamy Caramelised Onion Spaghetti is a comforting pasta dish that combines slowly browned onions with a creamy, spicy, and savory sauce. The addition of soy sauce adds extra umami, while chili oil brings a delicious kick.

Finished with fresh basil, mozzarella or Parmesan, and an extra drizzle of chili oil, this easy pasta makes a rich and satisfying meal.

Enjoy your creamy caramelised onion spaghetti! 🍝🧅🌶️