In a small bowl, combine oyster sauce, fish sauce, light soy sauce, MSG optional, and sugar, and hot water. Mix to combine and sugar is dissolved and set aside.
Cook noodles to package directions and drain well and set aside, reserving a cup of the noodle cooking water for the sauce to use as needed.
In a large pan over medium low heat, melt butter, then add minced garlic and sauté for 2 minutes until fragrant but not browned. Add the sauce and bring to a low simmer and cook for 2 minutes to reduce slightly, then add the crab and mix in to warm through.
Turn the heat up to high, then add cooked noodles. Mix well until the noodles are combined with the butter, garlic, sauce, and crab and continue cooking for another 1-2 minutes and the noodles are fragrant.
Garnish with scallions and enjoy!
