Crush 28 wafers finely. Beat egg whites in large bowl with mixer on high speed until soft peaks form. Gradually add sugar, beating until stiff peaks form.
Add wafer crumbs, baking powder and 1 tsp. vanilla; stir gently until blended.
Spread onto bottom of 9-inch pie plate sprayed with cooking spray. Stand remaining wafers around edge of pie plate.
Bake 1-1/4 hours or until egg white mixture is firm and lightly browned. Cool completely.
Beat cream and remaining vanilla in small bowl with mixer on high speed until stiff peaks form.