Prep and wash the chicken. Cook them in a bot of boiling water for 15-20 minutes, or until internal temperature is 165 degrees. Shred with two forks, and set aside.
Boil the water for pasta and cook according to directions.
While your pasta is cooking (it should take about 10 minutes to cook), prepare the sauce. In a medium bowl, whisk together the peanut butter, soy sauce, rice vinegar, 3 Tablespoons of toasted sesame oil, brown sugar, grated ginger and Sriracha. Sauce will be thick, but it will thin out when it hits the hot pasta.
Drain the pasta and return to the cooking pot. Toss with the remaining 2 Tablespoons of toasted sesame oil. This will keep the sauce from sinking in to the pasta too quickly.
Now, add in the minced garlic, scallions and shredded chicken. Using tongs, toss to distribute evenly.
Pour the sauce over the pasta, and mix well.
Plate and garnish with chopped peanuts and/or sesame seeds.