Prepare the broth by combining vegetable broth, soy sauce, and miso paste in a large pot.
Sauté the mushrooms and carrots in sesame oil until tender.
Add the sautéed vegetables to the broth and simmer for 10 minutes.
Cook the ramen noodles separately according to the package instructions, then drain.
Stir in the baby spinach just before serving, allowing it to wilt.
Assemble the bowls by placing noodles in each and ladling broth and vegetables on top.
Top each bowl with sliced green onions and a sprinkle of sesame seeds.