Bring a large pot of water to a boil, add salt and cook pasta according to package instructions. When pasta is cooked strain & set aside.
While pasta is cooking heat a large pan over medium heat. When hot add butter. Once the butter is mostly melted add the mushrooms. Cook the mushrooms for 3 to 4 minutes until browned and soft.
Add the minced garlic to the pan and cook another minute before adding the finely chopped sage. Cook the sage for 2 minutes until it is fragrant and appears slightly browned. Season the mushroom-butter mixture with salt & pepper.
Combine 1 cup of unsweetened coconut milk & cornstarch together in a measuring cup. Mix well to dissolve any clumps. Turn the heat down to medium low and add coconut milk to the mushroom-butter mixture. Let the sauce thicken over medium low heat, cooking for 3 - 4 minutes. If you find it thickening slowly up the heat to medium.
Add the cooked pasta to the pan and mix to combine until pasta is well coated with sauce. Remove from heat, plate and top with vegan parmesan and freshly chopped basil.