Heat a large skillet over medium-high heat. Add 4 teaspoons of butter and sauté the chopped garlic and shallots.
Chop and add all the mushrooms. Allow to cook down for 10-15 minutes. This will allow the water to evaporate.
After 10-15 minutes, season with salt and pepper and add sherry. Allow the mixture to cook down again until all liquid has evaporated. Set aside.
Separate the filo dough into groups of three sheets. Add your first three sheets to the pie dish and brush with melted butter and sprinkle with parsley. Add another three sheets and brush with butter and sprinkle with parsley. Add three more sheets of filo dough. Pour the mushrooms into the pie dish and spread evenly. Fold over the edges of the filo dough that hang over the sides of the dish.
Bake for about 20 minutes or until the dough is flaky and golden brown.