For the crust: Dice the margarine and return it to the refrigerator while you prepare the flour mixture. Place the flour, salt, and sugar in the bowl of a food processor fitted with a steel blade and pulse a few times to mix. Add the margarine and shortening. Pulse 8 to 12 times, until the margarine is the size of peas. With the machine running, pour the ice water down the feed tube and pulse the machine until the dough begins to form a ball. Dump out onto a floured board and roll into a ball. Wrap in plastic wrap and refrigerate for 30 minutes.
Cut the dough in half. Roll each piece on a well-floured board into a circle, rolling from the center to the edge, turning and flouring the dough to make sure it doesn't stick to the board. Fold the dough in half, place in pie pan. Repeat with the top crust.
For the cherry filling: Mix all ingredients and set aside while making crusts. Spray the bottom of a pie pan with PAM Bakers and then put first crust in bottom of pan. Sprinkle 1 tablespoon flour on inside of bottom crust. Fill crust with cherry mixture. Put other crust on top of pie. Fold top crust slightly under bottom crust all around the edge of the pie. Add cherry crust cut-outs to edges of pan. With extra crusts, make some cherry cut-outs and put them in a circle in the middle of the pie. Trim pie around the edges. Beat one egg with 1 tablespoon water and brush mixture over pastry and edges. Sprinkle with sugar. Take a sharp knife and make four slits in the pastry to let out the steam. Bake for 15 minutes at 400 degrees, then turn oven down to 350 degrees for the remaining 45-55 minutes. If edges start to brown too quickly, place aluminim foil over them. Pie is done when golden brown and some filling may be bubbling out.