These zesty and fresh slices are great for taking on a summer picnic.

Makes 20 pieces

Ingredients

• 250g digestive biscuits
• 100g desiccated coconut
• 100g butter, melted
• 7 limes
• 5 medium eggs and 1 egg yolk
• 350g caster sugar
• 100g plain flour
• sifted icing sugar, to serve

Method

1. Preheat the oven to 180°C, fan 160°C, gas 4. Line a 3cm-deep 20 x 30cm tin with baking paper.
2. Break the biscuits into a food processor and pulse to fine crumbs. Add the desiccated coconut and pulse again. Pour in the melted butter and the zest of 4 of the limes, then pulse until the mixture forms clumps.
3. Press the mixture into the prepared tin and bake for 10 minutes. Leave to cool completely.
4. Lower the oven temperature to 160°C, fan 140°C, gas 3. Put the eggs and yolk, sugar and flour in a bowl and whisk until smooth.
5. Juice all 7 of the limes until you have 200ml juice – gradually whisk this juice into the mixture until combined and smooth. Sieve the mixture on to the cold biscuit base.
6. Bake for 20-25 minutes until just cooked with a hint of wobble in the centre. Cool and chill until firm. Dust with icing sugar and cut into squares to serve.

Tip

Make up to a day ahead, store in an airtight container and keep in the fridge