Begin by bringing a large pot of water to boil. Once boiling, gently add the chicken breasts and poach them for about 15-20 minutes until cooked through. Remove from the pot, let cool slightly, then shred the chicken with two forks.
In a separate large saucepan, heat sesame oil over medium heat. Add minced garlic and grated ginger, sautéing for about 1 minute until fragrant.
Pour the chicken broth into the saucepan and bring it to a simmer. Add the sliced shiitake mushrooms and soy sauce to the broth, letting it cook for about 5 minutes.
Add the ramen noodles to the broth, cooking according to package instructions (usually about 3-4 minutes). Stir occasionally to break apart the noodles.
Once the noodles are cooked, add the baby spinach and shredded chicken to the pot, allowing the spinach to wilt for 2 minutes.
Taste the broth and season with salt and pepper if needed.
If using, softly boil the eggs by cooking them in boiling water for 6-7 minutes, then transfer to an ice bath before peeling.
To serve, ladle the ramen into bowls and top each bowl with a soft-boiled egg (halved), sliced green onions, and a sprinkle of sesame seeds.
Notes
Serve the ramen in deep bowls, garnished with extra green onions and a sprinkle of sesame seeds for an inviting look. Consider serving with chopsticks and a small side of soy sauce for added flavor.