Heat a pot of water to cook the noodles.
Add the noodles to the pot of water. Cook until al dente and still very chewy. Reserve some of the noodle water. Drain the noodles from the water.
Meanwhile, heat a wok or skillet over medium heat.
Melt the butter. Add in the white parts of the green onion.
Allow to lightly brown before adding the garlic. Sauté the garlic until aromatic, around 1 minute.
Lower the heat. Add in the soy sauce, dark soy sauce (if using), vegetarian oyster sauce, and sugar. Mix well and feel free adjust to your taste.
Leave for 1-2 minutes or until the sauce starts to caramelize from the sugars.
Add the noodles into the sauce. Mix well. Add some pasta or noodle water to loosen the noodles.
Taste the noodles and season with more veg oyster sauce or soy sauce and more sugar (to sweeten), if needed.
Finish the noodles with chili oil and sesame oil, if desired.
Serve while hot and enjoy!