In a small saucepan, heat ¼ cup of olive oil over medium heat. Once shimmering, add minced garlic and chili flakes. Cook for 2-3 minutes until golden and fragrant, then remove from heat.

In a skillet, heat 2 tablespoons of olive oil over medium-low. Add sliced onions and salt. Cook for 20-25 minutes, stirring occasionally, until soft and caramelized.

In a large pot of salted water, boil pasta according to package instructions for 8-10 minutes. Reserve 1 cup of pasta water before draining.

Return skillet with caramelized onions to low heat; add reserved pasta. Toss together and gradually pour in reserved pasta water until desired consistency is reached.

Drizzle chili oil over the pasta, tossing well. Adjust seasoning with salt if needed. Serve immediately, garnished with Parmesan and herbs.