In a large pot, combine the chicken broth, water, soy sauce, and miso paste (if using). Bring to a gentle simmer over medium heat.
Add the chicken breasts to the pot. Let them cook for about 10-12 minutes, turning occasionally, until they are fully cooked.
Once cooked, remove the chicken from the broth and let it rest on a cutting board for a few minutes. Use two forks to shred the chicken into bite-sized pieces.
Add the ramen noodles to the simmering broth and cook according to the package instructions, typically 3-5 minutes until tender.
Just before the noodles are done, stir in the baby spinach or bok choy to wilt.
Divide the noodles and broth among 4 bowls. Top with shredded chicken, soft-boiled eggs, sliced green onions, and a sprinkle of sesame seeds.
Notes
Don’t overcook the chicken and use fresh vegetables for the best flavor.