Making Caramelized Onion Pasta with Chilli Oil is straightforward if you follow these simple steps:

1. Cook the Pasta: Bring a large pot of salted water to a boil. Add the pasta and cook according to package instructions until al dente. Drain and set aside, reserving about 1 cup of pasta water.

2. Caramelize the Onions: In a large skillet, heat 3 tablespoons of olive oil over medium heat. Add the sliced onions and sprinkle with sugar and a pinch of salt. Cook, stirring occasionally, for about 15-20 minutes, or until the onions are golden brown and caramelized.

3. Season the Onions: Once the onions are caramelized, add black pepper and red pepper flakes to the skillet. Stir well to combine and cook for an additional 2 minutes to enhance the flavors.

4. Combine Pasta and Onions: Add the cooked pasta to the skillet with the caramelized onions. Toss everything together, adding reserved pasta water gradually until the desired sauce consistency is achieved.

5. Finish with Chilli Oil: Drizzle the chilli oil over the pasta and toss to coat evenly. Taste and adjust seasoning with extra salt and pepper if needed.