This recipe yields 12 servings and is excellent for a quick nibble. The ingredients you’ll require include 175g of room temperature butter, the zest from 2 lemons, 75g of powdered sugar, 50g of caster sugar, 1 egg yolk, 225g of standard flour, 25g of cornflour, 1 tsp of fine salt, 1 egg white, 30g of poppy seeds, and a bit of flaky sea salt for the finish.
Firstly, combine the butter, lemon zest, and both types of sugar in the apparatus of a table mixer and whisk using the paddle attachment for roughly 3-4 minutes, until it attains a light, fluffy consistency. This process can also be conducted manually or with a portable whisk, though it might require additional time. Incorporate the egg yolk, and then gradually add and softly fold in the flour, cornflour, and salt until a crude dough forms. Shift this mixture onto a large parchment sheet and mould it into an approximate log shape with a diameter of about 8 cm, or a longer, thinner log if you prefer. Wrap this securely in plastic film and chill in the refrigerator for a minimum of two hours.
Heat the oven to 170-degrees and then remove the shortbread dough, applying a generous coating of egg white using a pastry brush. Transfer your poppy seeds to a flat dish and roll your dough log in the seeds until completely covered. Slice the seeded log with a sharp knife into rounds – you should end up with 12-15 pieces.
Place the slices on a lined baking tray, spacing them evenly and allowing ample room in between as they will expand slightly while baking. Garnish with flaky sea salt and bake for 25-30 minutes, until crispy and golden brown. Let them cool completely before serving.