These elegant cookies have pink peppercorns that are not only pretty, but great counterpoints to the sweet cookies and tangy lemon filling. Slideshow: Delicious Sandwich Cookies
Preheat the oven to 350° and line 2 baking sheets with parchment paper.
In the top of a double boiler filled with 2 inches of simmering water, combine the egg yolks, confectioners’ sugar, lemon juice and zest. Cook over moderately low heat, whisking constantly, until thickened and an instant-read thermometer inserted in the curd registers 180°, about 10 minutes. Remove from the heat and whisk in the butter. Strain the curd into a heatproof bowl. Press a sheet of plastic wrap directly onto the surface and refrigerate until chilled.
In a food processor, combine the confectioners’ sugar, almonds and pink peppercorns and process until powdery. Transfer the mixture to a large bowl and break up any lumps.
In the bowl of a standing electric mixer fitted with the whisk, beat 2 of the egg whites at high speed until soft peaks form. Turn the mixer to the lowest setting while the sugar syrup cooks. In a small saucepan, combine the granulated sugar with the water and cook until the syrup reaches 238° on an instant-read thermometer, about 5 minutes. Increase the speed to moderately high and carefully and slowly pour the hot sugar syrup into the beaten whites in a thin stream. Beat until the meringue is stiff and glossy, about 5 minutes.
Pour the remaining egg white over the almond mixture and scrape the meringue on top. Using a rubber spatula, fold everything together until completely combined. Transfer the meringue to a pastry bag fitted with a 1/2-inch plain tip.
Pipe 1-inch mounds of meringue onto the prepared baking sheets, about 1 inch apart. Give each baking sheet a firm tap on the table to release any air bubbles. Rotate the pans and tap again. Using slightly moistened fingertips, press the meringues so they are about 1/4 inch high. Let stand at room temperature for 30 minutes to allow the tops to dry.
Bake 1 sheet at a time in the center of the oven for 10 minutes, until the meringues are lightly browned. Let cool completely on the baking sheet, then carefully lift off the macarons.
Scrape the lemon curd into a pastry bag fitted with a 1/4-inch plain tip. Pipe the lemon curd onto the flat side of half of the macarons and top them with the remaining cookies. Pipe a tiny dot of lemon curd on top of each one and garnish with a tiny rose petal.
The lemon curd can be refrigerated for up to 4 days.