Serves: 24 stars1) Sift the icing sugar. Put 60g of the sifted icing sugar, 280g of the almonds and all the cinnamon in a food processor. Process until the nuts are finely ground, with just a few larger pieces.
2) Whip the egg whites in a large, clean bowl with an electric mixer on high speed until they hold soft peaks, about one minute. Gradually add the remaining icing sugar while whipping, until the whites are thick, creamy and somewhat stiff, about two minutes more. Set aside two thirds of cup of this meringue for topping the biscuits. Fold the ground almond mixture and the lemon zest into the remaining meringue to make a stiff dough.
3) Preheat the oven to 120°C / gas mark 1/2, or the oven's lowest setting. Line two baking sheets with parchment paper or silicone baking mats.
4) Lay a sheet of parchment or waxed paper on the work surface and lightly dust with icing sugar. Turn the dough out onto the dusted paper, flatten and dust with more sugar as needed, and then lay another sheet of parchment or waxed paper on top. Roll the dough between the papers until it is about 1/2cm thick. Flip the dough over and gently peel off a sheet of the paper. For ease when cutting, lay the paper back on the dough, flip again and gently pull off the other side of the paper so that the dough is fully released from it.
5) Cut the biscuits with a 7.5cm star cutter and place about 5cm apart on the prepared baking sheets. (Excess dough can be rerolled.) Use a small spoon, brush or offset spatula to spread the reserved meringue over the top of each star, taking care not to let the meringue drip over the sides. Press or sprinkle the remaining sliced almonds in a decorative pattern into the meringue.
6) Bake the biscuits until the bottoms are light golden brown and the meringue is set and crisp, about 30 mins. Turn off the oven and open the oven door to release heat and dry out the biscuits in the oven for 10 more mins.
Busy Baker's Tips: The dough can be frozen between the sheets of paper for up to 2 weeks.
Store baked cookies in an airtight container for up to 10 days.