Heat 2 tablespoons of olive oil in a large skillet over medium heat. Add 1 large thinly sliced yellow onion and a pinch of salt, cooking for 25-30 minutes until golden brown and caramelized. Add 3 minced garlic cloves during the final 5 minutes.

In a small saucepan, heat 3 tablespoons of olive oil over low to medium heat. Add 1 thinly sliced garlic clove and sauté until fragrant, about 1-2 minutes. Stir in 1 tablespoon of red chili flakes and 1 teaspoon of paprika, cooking for an additional 2-3 minutes. Mix in 1 teaspoon of soy sauce.

Bring a large pot of salted water to a boil. Add 12 ounces of pasta—spaghetti, penne, or linguine—and cook according to package instructions until al dente. Reserve 1 cup of pasta water, drain the pasta in a colander.

Return the drained pasta to the pot over low heat, mix in the caramelized onions and chili oil. Toss until evenly coated, adding reserved pasta water as needed to achieve desired consistency.

Serve hot, garnished with grated Parmesan cheese, chopped fresh basil or parsley, and extra chili flakes if desired.