Blind bake the crust: Line the pie shell with aluminum foil and weight it with pie weights or beans. Bake for 15 to 20 minutes until light golden brown.
Increase oven temperature to 375 degrees F.
In a large skillet, heat oil over moderate heat. Add onion and cook until softened. Turn up heat to moderately high. Add pimentos, garlic, and spinach and cook, stirring until just heated through. Drain off any excess liquid. Beat the eggs in a bowl and add the Parmesan and milk. Add the spinach mixture and feta, and pour into the pie shell. Bake on a sheet pan in the middle of the oven for 30 to 35 minutes or until just set.