Heat 1 tablespoon neutral oil in a large pot. Add the leeks and cook for 3 minutes.

Add the butternut squash to the leeks and season with salt and pepper. Cook for 5–6 minutes until it just begins to brown around the edges.

Add the soy sauce, mirin, sesame oil, and maple syrup and toss to coat. Pour in the stock or water and bring to a boil. Reduce heat and simmer for 30 minutes until the squash is very tender.

Use an immersion blender to blend the broth until smooth and creamy. Pour in the coconut milk and shichimi togarashi and simmer for 10 minutes—taste and season to preferences.

Bring a pot of water to a boil and cook the noodles according to package instructions. Drain and set aside.

Heat the remaining 2 teaspoons oil in a skillet over medium-high heat. Add the mushrooms and cook for 4–6 minutes (depending on variety) until they brown and crisp up. Add the brussels sprouts and continue cooking until they car and begin to soften, about 8–10 minutes depending on the size. Adjust the heat as necessary to prevent them from burning—season with salt and pepper.

Divide the cooked noodles between bowls and ladle the broth into the bowl. Pile the charred vegetables on top and garnish with more shichimi togarashi and a drizzle of chili oil.