Heat the butter in a small saucepan until melted. Add the mushrooms and sauté over medium heat until browned; 8 – 10 minutes.
Gently pour in the heavy cream and simmer on medium-low for 5 minutes, until thickened.
Stir in the spinach and black pepper.
Open a package of RAMEN Z, adding the noodles and soup. Toss gently to incorporate.
Transfer to a serving bowl and drizzle with balsamic vinegar. Stir lightly and enjoy hot!