Cook pasta: Boil 5–6 ounces of pasta in salted water until al dente. Reserve at a 1/4 cup of pasta water.
Sauté aromatics: In a large skillet, heat olive oil over medium heat. Add mushrooms and cook until they release moisture and turn golden brown. Stir in shallot and garlic, cooking until fragrant.
Add seasoning: Mix in red chili flakes and optional herbs. Deglaze with a splash of pasta water to prevent garlic from burning.
Build the sauce: Pour in the heavy cream and stir until warmed through. Add parmesan, miso paste, soy sauce, and black pepper. Whisk gently to emulsify into a creamy sauce.
Combine pasta and sauce: Toss the cooked pasta into the skillet, adding reserved pasta water as needed to loosen and coat every strand.
Finish with butter: Stir in butter for a glossy finish. Taste and adjust seasoning.
Garnish: Top with parsley, chili flakes, and extra parmesan before serving.
Notes
Storage: Keep in the fridge up to 3 days. Reheat with a splash of cream or water.Substitutions: Use half-and-half instead of cream, or red miso in smaller amounts if you want stronger flavor.Freezing: Not recommended—cream sauces tend to split when thawed.Ingredient tip: Freshly grated parmesan melts best. Avoid pre-shredded for a smoother sauce.