Instructions

• Pulse flour, powdered sugar, salt, lemon zest and lavender in a food processor until combined.
• With the processor running, add butter one tablespoon at a time until moist and crumbly.
• Add vanilla and lemon juice and process just until a dough ball forms.
• Gather dry bits, shape the dough into a disk and lightly dust with flour.
• Line an 8- or 9-inch square pan with parchment and press the dough into an even layer.
• Cut the dough into squares; use 5 by 5 sections for 25 cookies in an 8-inch pan, or 6 by 6 for 36 in a 9-inch pan.
• Prick the dough all over with a toothpick or skewer to dock it.
• Refrigerate the shortbread for 30 minutes.
• Heat the oven to 300 F with a rack in the center.
• Bake about 45 minutes, until golden brown and baked through.
• Immediately recut the shortbread, then cool completely in the pan before lifting it out.
• Stir powdered sugar and meringue powder with lemon juice until smooth and drizzly.
• Dip cookie tops into icing, shake off excess, and decorate with lavender or zest before it sets.
• Let icing dry and set completely for at least 4 to 6 hours.
• Store airtight at room temperature for 1 to 2 weeks or freeze for 3 to 6 months.