Preheat oven to 425 degrees. In a large skillet over medium-high heat, melt butter and saute onions; when they are tender, add mushrooms and cook until lightly browned. Meanwhile, place the cubes of cream cheese onto the bottom of the pie shell, distributing evenly. Next add the cooked onions and mushrooms, spreading evenly over the pie shell; add the spinach, again spreading evenly. Sprinkle both grated cheeses over the vegetables. In a mixing bowl beat together the half-and-half and eggs; slowly pour mixture over the top of quiche. Bake at 425 for 15 minutes, and then reduce the oven temperature to 350 degrees and bake for another 30 minutes. Quiche should be golden brown.