Caramelize the onions by heating 2 tablespoons of olive oil in a skillet. Add the onions and salt, cooking for 25-30 minutes until golden brown. Add 3 minced garlic cloves in the last 5 minutes.

Prepare the chili oil in a saucepan. Heat 3 tablespoons of olive oil and add 1 thinly sliced garlic clove. Stir in 1 tablespoon of red chili flakes and 1 teaspoon of paprika for 2-3 minutes. Add 1 teaspoon of soy sauce and simmer for 2 minutes.

Boil salted water in a pot. Cook 12 ounces of pasta until al dente, reserving 1 cup of pasta water before draining.

Combine the drained pasta with caramelized onions and chili oil. Adjust sauce consistency with reserved pasta water as needed.

Serve topped with grated Parmesan, fresh herbs, and extra chili flakes if desired.