Finely dice the onion and mince the garlic.
Season the chicken thighs on both sides with the salt, black pepper, and garlic powder, rubbing the seasoning into the meat.
Bring a large pot of salted water to a boil and cook the pasta until 1 minute before al dente. Reserve 2 tablespoons of the pasta water before draining.
Heat a pan over medium-high heat with a bit of oil. Add the chicken thighs and sear for about 5 minutes per side, or until golden brown and cooked through. Remove from the pan and set aside.
Reduce the heat to medium and add a little more oil if needed. Add the onions and garlic and cook until softened and fragrant.
Stir in the heavy cream, light soy sauce, sugar, and reserved pasta water. Simmer until the sauce begins to thicken.
Return the chicken to the pan and coat it in the sauce, then remove it and set it aside.
Add the cooked pasta to the sauce and toss until every strand is coated and the sauce has reduced to a rich, creamy consistency.
Thinly slice the chicken and serve it over the pasta.
Optionally garnish with freshly grated Parmesan, black pepper, and chives.
