In a large, heavy bottomed pot, melt butter over medium heat. Add in onion, carrot and celery. Cook 5-7 minutes or until veggies start to tenderize.
Add in chicken, chicken stock, bay leaves, soy sauce, pepper and dried parsley flakes. Cover and bring to boil. Reduce heat to simmer and cook 20 minutes or until chicken is completely cooked.
While soup is cooking, make the homemade noodles: in a medium bowl, whisk egg, water and salt together. Slowly incorporate flour, first using a spoon and then switching to your hands. Knead until dough forms and becomes mostly smooth and moist, about 2 minutes. Set aside to rest 20 minutes.
Remove chicken and shred. Place back in pot.
Cut dough into two halves. Roll each half into 1/4 inch thick circles on floured board. Cut lengthwise into skinny strips and then across to create 1 1/2 inch noodles using a pizza cutter or sharp knife. Separate noodles and drop into simmering soup. Noodles will be cooked when they float.
Taste soup, adjust seasoning and serve hot.
*Chicken stock sodium levels vary by brand, so be sure to taste before adding in soy sauce. Start with 1 teaspoon and work your way up. It adds great umami flavor!