125g (2/3 cup) caster sugar

150g (2/3 cup) softened butter

1 duck egg

250g (2 cups) gluten free plain flour, plus a tbsp for dusting

1 tsp gluten free baking powder

1 x 397g tin condensed milk

Juice of 4 lemons

125g (2/3 cup) caster sugar

3 duck egg yolks

3 duck egg whites

75g (3/8 cups) caster sugar

75g (3/4 cups) sifted icing sugar

Zest of 4 lemons

2 tbsp demerara sugar (or you can use granulated sugar)

It's my birthday coming up (wahoo!) and so I wanted to bake something for work. I have a colleague who is a celiac, so I always make sure my work bakes are gluten-free. Another can't eat hen eggs, but can have duck eggs. Duck eggs are much richer and hence more delicious than hen eggs, so these lemon meringue slices use duck eggs in the curd filling and meringue topping.Duck eggs aren't too tricky to find either - Iceland in the UK sell them now! Lots of farm shops also stock them.I used Asda gluten free plain flour, but other gluten-free varieties should also work.Makes 20 squaresFor the biscuit base:For the curd filling:For the meringue topping:For the topping:1. Grease the base of a 20 x 20cm square cake tin and dust with a little gluten free plain flour.2. Beat the butter and sugar together in a mixing bowl until the mixture has lightened in colour and is creamy.3. Add the egg, gluten-free flour and gluten-free baking powder, and stir into the mixture. The dough will be very soft.4. Gently press the dough into the prepared cake tin, trying to get it as level as possible. Chill for 20 minutes.5. Preheat your oven to 180c (160c fan)/355f/gas mark 4.6. Use a fork to prick all over the top of the biscuit, then bake for 15-20 minutes, or until the top is golden.7. Whilst baking, make the lemon filling by pouring the lemon juice, condensed milk, sugar and egg yolks into a mixing bowl.8. Whisk until smooth.9. When the base is cooked, remove from the oven. Pour over the lemon filling and return to the oven for 5 minutes, until it is just set. Remove from the oven whilst you prepare the meringue.10. In a grease-free bowl, pour in the egg whites. Start whisking (I used a stand mixer but an electric hand whisk will also work) on a medium speed until it turns white and forms stiff peaks.11. Add the caster sugar, a tablespoon at a time, constantly whisking. Once all of the caster sugar has been added, turn the speed of the mixer up and whisk until the meringue forms stiff peaks when the whisk is lifted from the mix.12. Briefly whisk in the icing sugar.13. Spread the meringue over the lemon filling.14. Mix the demerara sugar and lemon zest together and sprinkle over the meringue.15. Bake for 10-15 minutes until crisp and golden.16. Leave to cool completely before removing from the tin and slicing into squares.17. Store in an airtight container.18. Enjoy!