PREHEAT oven to 325°F. Finely crush 35 of the wafers; place in medium bowl. Melt 1/4 cup of the butter. Add to wafer crumbs along with 2 Tbsp. sugar; mix well. Press firmly onto bottom and up side of 9-inch pie plate. Melt remaining 1 Tbsp. butter. Coarsely crush remaining 10 wafers; place in small bowl. Add melted butter; mix well. Set aside for later use.

PLACE sweet potatoes, cream cheese, 1/4 cup sugar, the corn syrup, eggs, spice and vanilla in medium bowl. Beat with electric mixer on medium speed until mixture is well blended. Pour into crust.

BAKE 1 hour to 1 hour 5 min. or until knife inserted in center comes out clean, topping with the wafer mixture and marshmallows after 55 min. Cool completely on wire rack. Refrigerate until ready to serve. Store leftover pie in the refrigerator.