Make the dough: In a food processor, pulse the flour and salt. Blend in the shortening until the mixture resembles coarse meal. Add enough of the ice water to make a soft but not sticky dough, tossing with a fork. Form the dough into a ball, flatten slightly, and dust with flour. Wrap the dough in waxed paper and chill for at least 1 hour.
Roll the pastry so it will extend about 1 1/2 inches beyond the sides of a 9 by 9 by 2-inch pan. Invert the pan on the pastry and cut around it, leaving a margin of about 1/2 inch. The amount of pastry used will depend upon whether you prefer a thick or thin crust. Roll the trimmings slightly wider.
Make the filling: In a small saucepan bring the raisins and rum to a simmer. Remove the mixture from the heat and let stand for 15 minutes, or until the raisins have absorbed the rum. In a large bowl combine the sugar, flour, spices, salt, and lemon zest. Add the apples and raisins and toss to coat well. Sprinkle with the lemon juice and mound into the pan. Dot with butter. Place the crust over the apple mixture and moisten the edges to seal the dough. Cut slits or a design on top to allow for the escape of steam, and crimp the edges. Brush with half and half. Bake in a 450 degree preheated oven for 15 minutes. Reduce the heat to 350 degrees and bake 25 to 40 minutes longer, depending on the variety of apples used.
Recipe courtesy of Sara Moulton