In a large skillet, heat 2 tablespoons of olive oil and 1 tablespoon of butter over medium heat. Once the butter melts, add 3 sliced onions and a pinch of salt. Cook for 25-30 minutes, stirring occasionally, until golden brown.

Sprinkle in 1 teaspoon of sugar halfway through cooking the onions to enhance sweetness. Stir frequently to prevent sticking.

In a small saucepan, heat 1/4 cup of olive oil over low heat. Sauté 2 minced garlic cloves for about 30 seconds. Stir in 1 teaspoon of chili flakes and 1/2 teaspoon of smoked paprika. Remove from heat.

Bring a large pot of salted water to a rolling boil. Add 8 ounces of pasta and cook according to package instructions, usually around 8-12 minutes for al dente. Reserve 1 cup of pasta cooking water before draining.

Return to the skillet with the caramelized onions and add the drained pasta. Gradually pour in reserved pasta water, stirring well to combine until desired sauce consistency is achieved.

Drizzle half of the prepared chilli oil over the pasta and toss gently. Adjust with more chili oil to taste.

Taste and adjust seasoning with salt and pepper. Give it one last toss to combine all flavors before serving.

Plate your pasta and garnish with fresh parsley and shaved Parmesan, if desired. Serve remaining chilli oil on the side.