Bring a large saucepan of water to a boil and cook the noodles according to package instructions. Meanwhile, heat the oil in a skillet over a low heat and add the garlic cloves. Saute until fragrant, about 30 seconds.
Turn up the heat and add the shimeji mushrooms and saute until the mushrooms are soft. Lower the heat and add a ladleful of cooking water from the noodles, the soy sauce, and the miso paste. Stir until the miso is dissolved well. Adjust seasoning with salt and pepper and bring the sauce to simmer.
Drain the noodles and add them to the sauce. Stir well to coat every noodle and serve with chopped parsley.