Lemon curd crumble bars

Preheat the oven to 190°C, gas mark 5; grease and line a 22cm square baking tin with parchment. In a food processor, pulse together the butter and fl our until soft crumbs form. (Alternatively, do this in a large mixing bowl, using your fi ngertips to rub the butter into the fl our.) Stir in the caster sugar and salt, then remove 1 /3 of the mixture (about 175g) and set aside in a bowl.

Add the baking powder, egg yolk and lemon zest to the remaining mixture in the food processor and continue to pulse until combined. Tip into the baking tin and press down to form an even layer. Bake for 15 minutes, then allow to cool for 10 minutes.

Meanwhile, add the demerara sugar, oats and nuts to the reserved mixture, with ½ tbsp water. Use a cutlery knife to mix everything together – it doesn’t matter if there are some clumps.

Spread the lemon curd over the biscuit base, then top with the crumble mixture. Bake for 20-25 minutes, or until lightly golden. Remove and allow to cool completely in the tin.

To serve, use a cutlery knife to carefully ease the parchment away from the caramelised edges of the curd. Remove from the tin and slice into bars. Store in an airtight container for up to 3 days.