Place noodles in a large bowl and cover with hot water. Set aside until noodles are softened, about 15 minutes.
Heat oil in a large skillet over medium heat. Add garlic and serrano chile and cook for 1 minute. Add chicken, fish sauce, light soy sauce, dark soy sauce, and molasses. Cook until chicken is no longer pink, 5 to 7 minutes. Add bell peppers, tomatoes, and cooked noodles; toss until mixed with the sauce and warmed through, about 5 minutes more. Reserve about 1 tablespoon basil; add the rest to the skillet and mix in. Garnish individual servings with reserved basil.