Prepare and roll out pastry. Line a 9-inch pie plate with the pastry. Trim and crimp edge as you like. Don't prick. Line pastry with a double thickness of foil. Bake in a 450 degree F oven for 8 minutes. Remove foil; bake for 4 to 5 minutes more or until mixture is set and dry. Remove pie plate from oven and reduce oven temperature to 350 degrees F.
In a medium saucepan, bring 2 cups of water to a boil; add rhubarb. Return to boiling. Drain off the water and cool the rhubarb.
Carefully sprinkle rhubarb evenly over bottom of prebaked piecrust.
In a bowl, beat together the eggs, milk, sugar, flour, butter or margarine, vanilla, and nutmeg. Slowly pour over rhubarb in piecrust. Cover the entire pie loosely with foil.
Bake in the 350 degree F oven for 25 minutes. Remove foil. Bake for 15 to 20 minutes more or until center appears nearly set when you shake it. Serve warm or chilled. Makes 8 servings.