Step 1: Heat 3 tablespoons olive oil in a large skillet over medium heat. Add sliced onions with 1 teaspoon salt and cook, stirring occasionally, for 25-30 minutes until deep golden brown and caramelized.

Step 2: Meanwhile, bring a large pot of salted water to boil and cook pasta according to package directions until al dente. Reserve 1/4 cup pasta water before draining.

Step 3: In a small saucepan, heat remaining olive oil over low heat. Add minced garlic, red pepper flakes, and smoked paprika. Cook for 2-3 minutes until fragrant but not browned.

Step 4: Add butter to the caramelized onions and stir until melted. Pour in white wine and cook for 2 minutes until slightly reduced.

Step 5: Add the drained pasta to the skillet with caramelized onions. Toss with pasta water to create a silky sauce.

Step 6: Remove from heat and drizzle with the warm chilli oil. Add half the Parmesan cheese and toss gently.

Step 7: Season with salt and pepper to taste. Serve immediately topped with remaining Parmesan and fresh parsley.