Preheat the oven to 325 degrees F (165 degrees C).
In a large glass or metal bowl, whip the egg whites until they can hold a peak. Gradually sprinkle in the sugar, while continuing to whip the egg whites to stiff peaks. Fold in saltines, vanilla, baking powder and pecans. Spread evenly into an ungreased 9 inch deep dish pie plate.
Bake for 30 minutes in the preheated oven, or until a skewer inserted into the center comes out clean. Remove from the oven, and cool. The crust will puff and crack as it cools.
When crust is completely cool, arrange sliced peaches over the top. Cover with aluminum foil to protect their color until serving. Top with sweetened whipped cream just before serving.