Heat oven to 350°f. Grease a 9-in pie plate. Unwrap chocolate bars; break into pieces.

Beat butter and sugar until blended in medium bowl. Add eggs; beat until light and fluffy. Stir in flour, Graham cracker crumbs and baking powder; beat until well blended.

Press half of dough onto bottom and up sides of pie plate. Spread marshmallow crime over bottom of crust. Set aside 1 tbsp chocolate bar pieces evenly over marshmallow creme.

Form remaing dough into ball; Place on sheet of waxed paper. With fingers, flatten and shape into 9-in circle. Pick up waxed paper. Pinch edges of dough together and form crust edge.

Bake 20-25 mind or until lightly browned. Cool completely in pan on wire rack. Melt remaing chocolate bar pieces with shortening; drizzle over top of pie.

To serve, microwave slices at HIGH (100%) 15-20 secs or until slightly warm and marshmallow starts to Melt. Top with ice cream, if desired.