Preheat the oven to 400°. Cut the asparagus 3 inches in length from the top of each spear; set tops aside. Cut stem ends into ¾ inch pieces.
In a small saucepan, bring water to a boil Add the ¾ inch asparagus pieces; cover and boil for 3-4 minutes. Drain and immediately and place asparagus in ice water. Once cooled drain the water and pat the asparagus dry.
On a lightly floured surface, roll out pastry into a 12" circle. Press onto the bottom and up the sides of an ungreased 9" tart pan with removable bottom; trim edges.
Place the blanched asparagus, ⅓ cup cheese and parsley in crust.
In a small bowl, combine the eggs, half and half, salt, cayenne and nutmeg; pour into crust. Arrange asparagus tops over egg mixture. Sprinkle with remaining cheese.
Bake for 25-30 minutes or until a knife inserted near the center comes out clean and the crust is golden. Allow to stand for 10 minutes before cutting.