Cookie recipe: Lemon Pistachio Buttercream Cookies

Line 2 rimless baking sheets with parchment paper or grease; set aside.

In large bowl, beat butter with sugar until fluffy; beat in egg and lemon rind and juice. Stir in flour in 2 additions to make smooth dough. Divide in half and shape into discs; wrap and refrigerate for 1 hour. (Make-ahead: Refrigerate for up to 24 hours.)

Between waxed paper, roll out each disc to 1/4-inch (5 mm) thickness. Using floured fluted 2-inch (5 cm) oval or 1-1/2-inch (4 cm) round cookie cutter, cut out shapes, rerolling scraps; slide onto baking sheet and refrigerate until firm, about 30 minutes. Place cookies, about 1 inch (2.5 cm) apart, on prepared pans.

Bake in top and bottom thirds of 325°F (160°C) oven, rotating and switching pans halfway through, until crisp and golden on edges, about 15 minutes. Let cool on pans on racks for 2 minutes; transfer to racks and let cool completely. (Make-ahead: Store layered between waxed paper in airtight container for up to 3 days or freeze for up to 1 month.)

White Chocolate Buttercream: Meanwhile, in bowl, beat butter with sugar until fluffy; beat in white chocolate and lemon rind and juice. Spread scant 1 tsp (5 mL) onto bottoms of half of the cookies; sandwich with remaining cookies.

Garnish: Drizzle tops with white chocolate; sprinkle with nuts. Refrigerate until firm, about 1 hour. (Make-ahead: Layer between waxed paper in airtight container and refrigerate for up to 1 week.)