We love the layers of flavor and texture in this rich, hearty soup. Smarts: Miso is the key flavor in the broth. Since every type of miso paste is different, be sure to taste your soup and add some more if needed.
Heat a wok or Dutch oven with cooking oil over medium-high heat. Add chicken and saute until chicken is golden brown and cooked through, 5 to 7 minutes. Set chicken aside.
Add first portion of stock to the pan and simmer for 1 minute, scraping up any brown bits from the bottom of the pan.
Add remaining stock, squash, miso paste, and rice vinegar. Cover and simmer until squash is starting to turn tender, ~8 minutes.
While soup simmers, bring a small saucepan of water to a boil. Gently add eggs to boiling water and boil for exactly 7 minutes (this should yield cooked whites and runny yolks so adjust time if you’d like your eggs cooked differently). When eggs are finished, transfer to a colander and run under cool water.
Add noodles to soup. Simmer noodles until tender (check the package since recommended cook times may vary). In the last minute stir in chicken, toasted sesame oil, and spinach until spinach is wilted. Taste and add some more miso if needed.
Peel eggs and slice in half.
Divide soup between serving bowls and top with eggs. Enjoy!