For an extra layer of flavor, try adding a sprinkle of grated Parmesan cheese to the filling. If you don't have Asiago cheese, you can substitute it with Pecorino Romano or a good quality Parmesan. To prevent the mushrooms from becoming soggy, be sure to cook the mushroom stems until all the excess moisture has evaporated. Feel free to experiment with different herbs and spices in the filling. A pinch of red pepper flakes or a dash of balsamic vinegar can add a nice touch. These stuffed mushrooms can be prepared ahead of time and baked just before serving.