Lemon meringue shortbread

Method

1. Heat the oven to 140°C fan/gas 3 and line the base and sides of the cake tin with baking paper.
2. To make the shortbread, beat the butter and sugar in a bowl with an electric mixer or wooden spoon until smooth. Stir in the flour and lemon zest, then work the mixture until the dough forms a smooth paste. Transfer the shortbread mix to the lined tin and press it down evenly into all corners using the back of a spoon, until it’s flat and even all over. Bake in the oven for 20-25 minutes until lightly golden all over.
3. While the shortbread is baking, make the lemon curd. Combine the lemon juice, agar agar flakes and sugar in a saucepan. Stir together, then slowly simmer over a low heat for 5-10 minutes until the sugar and agar have dissolved. Mix the cornflour with 1-2 tbsp water to make a thick paste, add this to the lemon syrup mixture and whisk in. Increase the heat and cook the mixture for 2-3 minutes, whisking continuously until it thickens (this will ensure the mixture doesn’t taste of raw flour, so taste it before adding the butter – be careful as it will be hot!). Remove the pan from the heat and gradually whisk in the cold cubed butter until smooth. The butter enriches the curd and mellows the lemon.
4. Lightly beat the 3 whole eggs in a mixing bowl, then pour in a third of the lemon mixture and whisk together. Stir in the remaining lemon mixture.
5. Once the shortbread is baked, remove from the oven and turn the temperature down to 120°C fan/gas 1. Pour the lemon curd mixture over the shortbread and spread it out to cover the base. Put the tin back in the oven and bake for 10-15 minutes until the curd is beginning to set but still has a slight wobble.
6. While the curd is baking, make the meringue. Mix together the sugars in a small bowl until evenly combined. Using an electric mixer or a stand mixer fitted with a whisk attachment, whisk the egg whites in a spotlessly clean bowl until soft peaks form. Gradually add the sugar to the egg whites, a spoonful at a time, whisking continuously for about 10 minutes until all the sugar has dissolved and the meringue is smooth and thick – you should be able to upturn the bowl without the meringue falling out.
7. Once the lemon curd layer has begun to set, remove the tin from the oven and spoon the meringue mixture over the top. Gently spread out the meringue evenly with the back of a spoon. Return the tin to the oven and bake for a further 10-15 minutes until the meringue forms a thin crust and colours slightly. Remove from the oven and leave to cool completely. Once cool, carefully remove the meringue shortbread from the tin and cut it into 15 even slices.