Macarons: Heat standard oven to 325°F. Sift powdered sugar, almond meal and cocoa powder into large bowl. Beat egg whites with electric mixer fitted with whisk attachment on medium speed until foamy. Gradually add superfine sugar, beating on high speed until stiff peaks form. Stir in vanilla. Fold in almond mixture by hand until egg white mixture is shiny. (Mixture will lose some volume.)
Spoon mixture into pastry bag fitted with #7 plain tip. Pipe onto parchment paper-lined sheet pans into 1-1/4-inch circles, from inside to outside. Let stand at room temperature 30 to 60 min. or until tops of cookies crust over.
Bake 15 to 18 min. or until cookies are set. Cool pan completely on wire rack before removing cookies.
Chocolate Filling: Bring cream to boil in heavy saucepan. Remove from heat; stir in chocolate until melted. Stir in OREO Pieces. Pour mixture into blender or food processor. Blend until smooth. Let stand at room temperature until cool. When ready to use, spoon into pastry bag fitted with #5 round tip.
Pipe 1/2 oz. Chocolate Filling onto 1 cookie. Cover with second cookie, pressing slightly to hold together. Repeat with remaining cookies. Store filled cookies at room temperature.