MOCHA SHORTBREAD

Steps:

• Position racks in top third and bottom third of oven and preheat to 325°F. Line 2 large baking sheets with parchment paper. Sift first 5 ingredients into medium bowl. Using electric mixer, beat butter in large bowl until fluffy. Beat in powdered sugar. Add dry ingredients and beat until well blended.
• Gather dough into ball; divide into 3 equal pieces. Place 1 dough piece close to each end of 1 prepared sheet. Place third piece in center of second prepared sheet. Using moistened fingertips, press each dough piece to 7-inch-diameter round. Using small sharp knife, mark each round into 8 wedges. Press fork tines around edge of each to make notched design. Bake shortbread 12 minutes. Reverse sheets. Bake until shortbread looks dry and feels firm to touch, about 12 minutes longer. Cool on sheets on racks. Cut shortbread into wedges along marked lines. Transfer wedges to work surface.
• Place white chocolate in metal bowl set over saucepan of barely simmering water. Stir until chocolate is melted and smooth. Place bittersweet chocolate in another bowl set over same simmering water. Stir until melted and smooth.
• Fit 2 pastry bags with 1/8-inch plain tips; spoon white chocolate into 1 and dark chocolate into other. Or, spoon chocolate into 2 small plastic bags (cut off 1 tip from each bag). Pipe chocolates decoratively over cookies. Let stand until chocolate sets, about 1 hour. (Can be made 2 days ahead. Store airtight in single layers between sheets of waxed paper.)