Macarons with Semisweet Chocolate Ganache

FOR THE MACARON SHELLS: Using pencil and 1½-inch round biscuit cutter as guide, trace thirty 1½-inch circles on each of 2 pieces of parchment (5 evenly spaced rows of 6 circles on each piece of parchment). Spray 2 baking sheets with vegetable oil spray. Place templates pencil side down on sheets and smooth to adhere. Sift flour, confectioners' sugar, and salt through fine-mesh strainer into large bowl and set aside.

Measure 75 grams of egg whites into bowl of stand mixer fitted with whisk attachment (reserve remaining whites). Add cream of tartar. Start mixer on medium-high speed and whip until soft peaks form, 2 to 3 minutes (see "A" in "Making the Shells"). Turn mixer to lowest speed and let run while you make sugar syrup.

Using heatproof spatula, gently stir sugar and water together in small saucepan. Cook over medium-high heat, without stirring, until sugar dissolves. Continue to cook, checking temperature frequently, until sugar syrup reaches 245 degrees, 4 to 5 minutes.

When syrup reaches 245 degrees, quickly remove pan from heat; adjust mixer speed to medium; and carefully pour syrup into whites in thin, steady stream (avoid hitting whisk; aim for side of bowl just above whites; see "B" in "Making the Shells"). Add food coloring; increase speed to medium-high; and continue to whip until meringue is just shy of stiff peaks (very tip of peak should bend to 2 or 3 o'clock), 3 to 5 minutes (see "C" in "Making the Shells").

Transfer meringue and reserved 38 grams egg whites to almond flour mixture. Using large rubber spatula, stir to incorporate. Turning bowl, stir and smear batter against sides of bowl, scraping sides and bottom frequently until batter loosens and flows from spatula in slow, wide stream for 8 to 10 seconds and reincorporates into batter within about 30 seconds (see "D" in "Making the Shells"). (To test consistency, place spoonful of batter on prepared sheet and let sit for 1 minute. If batter spreads into flat, smooth-topped disk, continue with recipe; if it remains domed, continue stirring, taking care not to overmix, and retest.)

Transfer batter to pastry bag fitted with ½-inch round tip. Hold bag perpendicular to sheet and about ½ inch above sheet. Using template as guide, pipe batter into 1½-inch-wide disks, keeping bag still as batter flows from tip. To finish each disk, use quick flick of your wrist to cut off batter stream (see "E" in "Making the Shells"). Rap sheets firmly on counter 6 times to release air bubbles. Let rest until shells form skin that can be touched gently with your finger without marring surface, about 20 minutes ("F" in "Making the Shells"). While shells dry, adjust oven rack to lower-middle position and heat oven to 325 degrees.

Bake 1 sheet of shells for 13 minutes. To test for doneness, place your finger gently on top of 1 shell and move it side to side; if center feels loose and jiggly, continue to bake, checking every minute, until firm. Transfer sheet to wire rack and bake remaining shells. Let shells cool completely on sheets. While shells cool, make filling.

FOR THE GANACHE: Place chocolate in heatproof bowl. Bring cream and corn syrup to simmer in small saucepan over medium heat (do not let cream boil). Pour cream mixture over chocolate and let stand 2 minutes. Stir until smooth and glossy. Cool, stirring occasionally, until ganache has consistency of soft frosting, 3 to 4 hours. Transfer to pastry bag fitted with ½-inch round or star tip. (Ganache can be refrigerated for up to 2 days; let stand at room temperature for 30 minutes before using.)

TO ASSEMBLE: Gently peel shells from parchment (see "G" in "Making the Shells"). (If shells don't release cleanly, place sheets in freezer for 10 minutes.) Holding 1 upturned shell in your hand, pipe about 2 teaspoons filling on top, leaving ⅛-inch border. Place second shell on top of filling, pressing gently until filling spreads to edges. Repeat with remaining shells and filling. Arrange cookies on clean parchment-lined sheet and wrap well. Refrigerate for at least 24 hours or up to 1 week or freeze for up to 2 months. Bring to room temperature before serving.