Line 2 large baking sheets with aluminum foil; prepare Piping Meringue.
Combine cornstarch and cocoa, mixing well; fold into meringue just until blended.
Spoon mixture into a decorating bag fitted with No.
4B star tip; pipe forty 3- x 1 1/2-inch rectangles using a zigzag motion.
Sprinkle lightly with 2/3 cup almonds.
Bake at 225° for 1 1/2 hours Turn off oven; cool in oven at least 2 hours or overnight.
Carefully peel foil from meringue fingers.
Store meringues in airtight container at room temperature up to 2 days.
Up to 2 hours before serving, pipe Chocolate Butter cream between 2 meringues fingers (flat sides together) using No.
18, 19, or 20 star tips; place on its side in a paper baking cup.
Repeat procedure with remaining meringue fingers and butter cream.
Sprinkle butter cream filling with remaining toasted almonds.
Refrigerate until ready to serve.