Preheat oven to 450 degrees F. Prepare and roll out Pastry for Single-Crust Pie or unroll refrigerated piecrust according to package directions. Line a 9-inch pie plate with pastry. Trim; crimp edge as desired. Do not prick pastry. Line pastry with a double thickness of foil. Bake for 8 minutes. Remove foil. Bake for 4 to 5 minutes more or until pastry is set and dry. Remove from oven. Reduce oven temperature to 325 degrees F.
Meanwhile, in a medium bowl stir together eggs, half-and-half, green onions, salt, pepper, and nutmeg. Stir in ham. In a small bowl toss together the cheese and flour. Add to egg mixture; mix well.
Pour egg mixture into hot baked pastry shell. Bake for 40 to 45 minutes or until a knife inserted near center comes out clean. Let stand for 10 minutes before serving.
Pastry for a Single-Crust Pie
In a medium bowl stir together flour and salt. Using pastry blender, cut in shortening and butter until pieces are pea size.
Sprinkle 1 tablespoon of the water over part of the flour mixture; toss with a fork. Push moistened pastry to side of bowl. Repeat moistening flour mixture, using 1 tablespoon of the water at a time, until flour mixture is moistened. Gather flour mixture into a ball, kneading gently until it holds together.
On a lightly floured surface use your hands to slightly flatten pastry. Roll pastry from center to edges into a circle about 12 inches in diameter.
Wrap pastry circle around the rolling pin. Unroll into a 9-inch pie plate. Ease pastry into pie plate without stretching it.
Trim pastry to 1/2 inch beyond edge of pie plate. Fold under extra pastry even with the plate's edge. Crimp edge as desired. Do not prick pastry. Fill and bake as directed in recipes.