Whisk together sauce ingredients and set aside.
Cook noodles according to package direction. Rinse and set aside in a colander.
Preheat a skillet or wok over medium heat and add oil. Add chicken breast and cook until browned and mostly cooked through. Turn off heat, drain some of the liquid and place back on stove. Push the chicken over to one side of the skillet and pour the beaten egg into the skillet in the space you’ve created and use your cooking spatula to scramble the egg in the skillet.
Add the cooked noodles to the skillet and then pour the sauce over the noodles. Reduce the heat a little at this point to more like medium-low. The mixture will be saucy at first but let it cook for another 2-3 minutes, stirring frequently. The noodles and proteins will soak up the sauce and it will thicken.
Remove from heat, and serve warm. Let diners add their own desired toppings.