1. Heat oven to 350°F. Grease 9-inch pie plate. Unwrap chocolate bars; break into pieces.
2. Beat butter and sugar until blended in medium bowl. Add egg; beat until light and fluffy. Stir in flour, graham cracker crumbs and baking powder; beat until well blended.
3. Press half of dough onto bottom and up sides of pie plate. Spread marshmallow creme over bottom of crust. Set aside 1 tablespoon chocolate bar pieces; sprinkle the remaining pieces evenly over marshmallow creme.
4. Form remaining dough into ball; place on sheet of waxed paper. With fingers, flatten and shape into 9-inch circle. Pick up waxed paper, supporting dough with hands. Flip dough onto pie surface; peel off waxed paper. Pinch edges of dough together and form crust edge.
5.. Bake 20 to 25 minutes or until lightly browned. Cool completely in pan on wire rack. Melt remainig chocolate bar pieces with shortening; drizzle over top of pie. 8 to 10 servings.
To serve, microwave slices at HIGH (100%) 15 to 20 seconds or until slightly warm and marshmallow starts to melt. Top with ice cream, if desired.