Ingredients

Step by step

1. Preheat the oven to 180°C, fan 160°C, gas 4 and line two baking trays with baking paper. Sift the flour, custard powder and icing sugar into a mixing bowl. Add a pinch of salt and stir to combine. Add the butter and rub in with your fingertips until the mixture resembles breadcrumbs. Add the lemon zest and poppy seeds and stir in with a cutlery knife, then continue to rub with your fingertips until the mixture starts to clump together. Use your hands to bring together into a dough.

2. Take 18-20g pieces of the dough and roll into 3.5cm round balls. Space them slightly apart on the prepared trays. You should end up with 20 balls. Use a floured fork to press down on the balls to create lines and flatten them to about 4cm diameter.

3. Bake for 18-20 minutes, swapping the trays around halfway, until very pale golden. Leave to cool completely on the trays.

4. For the buttercream, use a handheld electric mixer to beat the butter until very soft. Gradually beat in the icing sugar, starting on a low speed and slowly increasing. Add the lemon juice and beat for a further 1-2 minutes until creamy.

5. Turn half the biscuits upside down, then pipe or spoon on the buttercream. Sandwich with the remaining biscuits, so the forked sides face outwards. Chill for 30 minutes to set the buttercream, then arrange on a serving plate or board and lightly dust with icing sugar. Return to room temperature (about 30 minutes) before serving. Store for up to 5 days in an airtight container in a cool place.