Heat olive oil in a large pot over medium heat. Add the minced garlic and sauté for about 1 minute until fragrant. Toss in sliced mushrooms and cook until tender and golden, about 3-5 minutes.

Pour in the spaghetti or fettuccine along with the vegetable broth, ensuring the pasta is fully submerged. Bring to a gentle boil.

Stir in the miso paste, soy sauce, and sesame oil. Mix thoroughly to ensure even coating.

Cover the pot and simmer until pasta is al dente, about 10 minutes, stirring occasionally.

Taste and adjust seasoning with salt and pepper as needed. Serve warm, garnished with green onions or sesame seeds.