1. Heat oven to 300 degrees. Lightly grease 9-inch pie plate.
2. In 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 rubber scraper, fold in graham crackers and pecan pieces. Spoon into pie plate.
3. Bake 30 minutes or until wooden pick inserted in center comes out clean. Cool completely on wire cooling rack.
4. In chilled small bowl using chilled beaters, beat cream just until it begins to thicken. Add remaining1/4 cup sugar and vanilla and continue beating until stiff peaks form. Do not over beat. Top pie with whipped cream. Sprinkle with pecans and refrigerate until served.