Bring a pot of water to a boil and cook the noodles until one minute short of al dente. Rinse under cold water and drain well.
Melt the butter in a pan over medium heat. Once fully melted, add the dark soy sauce, light soy sauce, and sugar, and bring everything to a simmer.
Add the drained noodles to the simmering sauce and toss until the sauce has soaked into the noodles and coats every strand.
Transfer to a bowl and optionally garnish with sesame seeds and scallions.
