FILLING AND ASSEMBLY: Heat oven to 450 degrees. Mix all ingredients together at medium speed of electric mixer, blending thoroughly. Pour into pie shell and bake at 450 degrees for 5 minutes. Reduce heat to 325 degrees and continue cooking for 45 minutes, or until pie is set. Let cool about 10 minutes before serving. PIECRUST: Mix flour and salt together in a bowl. Cut vegetable shortening into flour until mixture resembles course meal. Sprinkle with ice water, 1 tablespoon at a time, mixing quickly with a fork after each spoonful. Add only enough water so dough holds together and can be formed into a ball. Divide dough into 2 equal portions and form each into a smooth ball, handling as little as possible. Roll one portion out onto lightly floured surface. Place rolled dough in a 9-inch pie plate; trim and flute edges.