CHEDDAR PIE CRUST: Combine the flour, cheese and salt in a bowl. Using a pastry blender or two knives, cut in the shortening until coarse crumbs form. Sprinkle the iced water (5 or 6 tbls will be needed) and using a fork, toss the crumbs until a dough is formed. Press the dough firmly into a ball.
Divide the pastry almost in half and roll out the larger half, on a lightly floured surface, to a 13-inch circle. Line a 9-inch pie plate with the pastry, trimming the edges to 1/2-inch beyond the rim of the pie plate. (Note: When lining the pie plate, be careful not to stretch the pastry when spreading it out. This will cause holes or the pastry will shrink and the filling will run over in the oven as it is baked. Place in the pie plate and gently, working from the center, spread the pastry out until it covers the bottom of the pie plate and then lay the rest of the pastry over the rim and trim.)
FILLING: Combine the apples, sugar, flour, and cinnamon in a bowl, mixing well. Arrange the apple mixture in the pastry lined pie plate. Roll out the remaining pastry to an 11-inch circle. Gently fold into quarters and cut steam slits in the folds. Unfold the crust and place on top of the filling, trimming the crust to 1-inch beyond the rim of the pie plate. Fold the top crust under the lower one and flute to form a ridge around the edge of the pie plate. Combine the egg yolk and water, then brush the mixture over the top crust and rim. Bake in a 400F oven for 45 to 50 minutes or until apples are tender and the crust is a golden brown. Cool on a wire rack until slightly warm and serve with Vanilla Ice Cream, if desired.
