Heat oven to 300°.
Measure flour, salt and baking powder into a bowl.
Cut in shortening thoroughly with pastry blender.
Add ice water a little at a time, mixing until all flour is moistened and dough almost cleans the side of the bowl (1-2 tbsp. water can be added if needed).
Gather dough into ball.
Place waxed paper on counter.
Sprinkle heavily with flour.
Place ball of pie dough onto waxed paper and sprinkle heavily with more flour; cover with more waxed paper.
(For two-crust pie, divide dough in half and shape into 2 flattened rounds.)
Roll dough 2 inches larger than inverted pie pan. (After 4 or 5 rolls with the rolling pin, I lift off the waxed paper and sprinkle more flour on top of dough to prevent sticking).
Gently remove top layer of waxed paper. Fold pastry into quarters; unfold and ease into pan.
Trim overhanging edge of pastry if necessary.
Roll out second layer of dough.
Once both layers of crust have been rolled out, add peach filling to the pie plate.
Dot with butter.
Add remaining pie crust on top of peach filling; cut slits so steam can escape.
Flute edges.
Bake at 300° until the filling is no longer soupy. The filling will bubble up very thickly through the slits in the crust. It may take two to three hours depending on how much peach filling you use.