Cook the Mushrooms: Preheat the pan on medium high temperature. Add the Grapeseed oil. Add the chopped onions and garlic. Sauté for six to eight minutes. Add the paprika powder. Add the mushroom and stir from time to time. Only add the celery salt or salt when the mushroom begins to release water. Make sure to add little at a time and taste to reach your desired level. After 5 minutes of cooking the mushrooms, add nutmeg powder and continue to cook the mushrooms until it is cooked. Add the white flour to thicken the sauce.
Cook the Pasta: Begin with cooking the pasta. Add a tiny pinch of salt in the pot. Cook 1 minute less than the time instructed on the packet. Make sure to put aside 1 cup of cooked pasta water before draining the water.
Mix the Mushroom: Transfer the pasta to the sauce. Toss gently to thicken the sauce and evenly coat the pasta. Add the optional garnish such as grano padano cheese and cooked sage leaves. If using the sage leaves as décor, cook on medium low heat with a small dollop of butter. Once the sage leaves have browned up. Add it to the top of the mushroom pasta. Serve.