Preheat oven to 350 degrees.
Beat egg whites in large bowl with electric mixer on high speed until soft peaks form.
Blend in vanilla. Gradually add sugar, beating after each addition until well blended. Continue to beat until stiff peaks form.
Mix cracker crumbs, pecans and baking powder. Add to egg white mixture; stir gently until well blended.
Spread into greased 9-inch pie plate. Bake 30 minutes and cool completely.
Top with whipped topping just before serving. Store any leftover dessert in refrigerator.
Option: you may jazz this pie up with fruit syrup and fruit if desired.