Name: Citrus bars
Prep time: 20 min
Cook time: 45 min
Total time: 1 h 5 min
Yield: Makes 18
Cuisine: British
Ingredients: 250g plain flour; 85g icing sugar plus extra for dusting; 175g butter cut into small pieces; 2 lemons and 1 large orange; 4 large eggs; 400g caster sugar; 50g plain flour

For the base

250g plain flour
85g icing sugar
plus extra for dusting
175g butter
cut into small pieces

For the topping

2 lemons
and 1 large orange
4 large eggs
400g caster sugar
50g plain flour

Method

step 1
Heat oven to 180C/160C fan/gas 4. Line the base and sides of a shallow rectangular tin (about 23 x 33cm) with baking parchment, snipping the corners so that it comes up the sides of the tin. Tip the flour, sugar and butter into a food processor and whizz until it forms fine crumbs. Tip into the prepared tin and smoothly level with the back of a metal spoon, pressing it down lightly. Bake for 20-25 mins until pale golden.
step 2
To make the topping, finely grate the zest from the lemons and orange and squeeze out all the juice. Measure the juice – you need 120ml. Whisk together the eggs and sugar using an electric whisk for 1 min, then add the citrus zest and juices, and whisk again briefly. Sift in the flour and whisk well to mix. Pour over the shortbread and bake for 15-20 mins until the topping has just set. Cool completely in the tin, then lift out of the tin using the lining paper. Dust thickly with icing sugar and cut into 3 down the length and 6 across to make 18 bars.