PREHEAT oven to 350° F. Grease 2 baking sheets.
UNFOLD 1 pastry sheet on lightly floured surface. Roll out to make a 10-inch square. Cut into 4 squares. Place 2 tablespoons morsels in center of each square. Brush edges lightly with beaten egg and fold squares to form triangles. Press edges to seal. Place on prepared baking sheet about 2 inches apart. Repeat with remaining pastry sheet. Brush top of each pastry with beaten egg.
BAKE for 15 to 17 minutes or until puffed and golden. Cool on baking sheets for 2 minutes; remove to wire racks to cool completely.
MELT broken baking bar and butter in small, uncovered, microwave-safe bowl on HIGH (100%) power for 30 seconds; STIR. If pieces retain some of their original shape, microwave at additional 10 to 15-second intervals, stirring just until smooth. Stir in sugar. Add water, stirring until icing is smooth, adding additional water, if necessary. Drizzle icing over pastries.