On the lightly floured surface, roll out about two thirds of the piecrust to a 13- to 14-inch circle and turn it into a 10-inch deep-dish pie plate.
In a large mixing bowl, combine the 1/2 cup granulated sugar, 1/4 cup flour and cinnamon. Add the apples and toss together. Turn mixture into piecrust.
In a medium bowl, mix rolled oats, 1/4 cup brown sugar and 3 tablespoons flour. Cut in butter until mixture resembles coarse crumbs. Sprinkle the oat mixture over the apple mixture.
Roll out remaining pastry and cut into 1/2-inch-wide strips. Weave over the top of the pie to form a lattice crust. (Jackie likes to make a flower with one strip and place on center.) Press ends of strips into crust rim. Fold bottom pastry over strips. Seal and crimp edge.
Brush the lattice top and crust with a mixture of the egg yolk and the water. To prevent overbrowning, cover the edge of the pie with aluminum foil.
Bake the pie in a 375 degree F oven for 25 minutes. Remove the foil. Bake for 25 to 30 minutes more or until filling is bubbly. Remove pie from oven and drizzle with caramel topping. Cool on a wire rack. Makes 8 to 10 servings.