Preheat oven to 350° F. Beat egg whites and baking powder until stiff peaks form. With mixer on high, slowly add the sugar. Add the vanilla. Slowly add in the cracker crumbs. Using a wooden spoon, fold in the pecans. Pour into a well-greased 9-inch pie plate and bake for 30 minutes. Cool, then top with fresh whipped cream. Refrigerate pie for 2 hours before serving.