Stir together first 6 ingredients in a large bowl. Combine egg, egg whites, and vanilla; stir until blended. Add egg mixture to flour mixture; stir well (mixture will be very crumbly). Stir in 1/2 cup morsels.
Knead mixture on an unfloured surface. Continue to knead until well blended. Shape into a 14" x 4" log on a lightly greased baking sheet. Bake at 350° for 30 minutes. Remove to a wire rack to cool 10 minutes.
Cut log diagonally into 3/4"-thick slices with a serrated knife, using a gentle sawing motion. Place slices on ungreased baking sheets. Bake 5 minutes; turn cookies over, and bake 5 more minutes. Cool on wire racks.
Microwave candy coating squares in an 11" x 7" baking dish at HIGH 1 minute. Stir in remaining 1 cup morsels. Microwave at HIGH 30 seconds; stir well. Dip 1 long side of each biscotti into chocolate mixture. Sprinkle with espresso beans. Let harden.