Preheat oven to 300° F. Place a small mixing bowl and beaters in the refrigerator to chill. Lightly grease a 9-inch pie plate.
In a large mixing bowl, beat egg whites and baking powder until soft peaks form. Add cream of tartar, beating constantly. Add 1 cup of the sugar, a tablespoon at a time, beating constantly until stiff peaks form. Using a rubber scraper, fold in graham cracker and pecan pieces. Spoon into prepared pie plate. Bake for 30 minutes or until a wooden pick inserted into center comes out clean. Cool completely on a wire rack.
In the chilled small bowl, beat whipping cream with chilled beaters just until it begins to thicken. Add remaining 1/4 cup sugar along with vanilla extract and continue beating until stiff peaks form. Do not over-beat. Top pie with whipped cream. Sprinkle with pecans and refrigerate until ready to serve.Makes 4 to 6 Source: