Pink grapefruit and coconut squares

Preheat the oven to 170°C/150°C fan/gas 3. Grease a 20cm square tin with butter and line the base and sides with baking paper.

To make the shortbread base, sieve the flour, icing sugar and a pinch of salt into a bowl. Add the grapefruit zest and coconut and stir to combine. Pour in the melted butter and mix again until the dough starts to clump together. Tip into the lined tin and use your hands to press the mixture evenly and firmly over the base. Bake on the middle shelf of the oven for about 25 mins until golden and firm.

For the topping, put the grapefruit zest into a large mixing bowl. Add the caster sugar and beat to combine. Then mix in the flour and stir again. Tip in the eggs and whisk until smooth. Pour in the grapefruit juice (approx. 250ml) and lemon juice, slowly add to the egg mixture, whisking until smooth. Add a few drops of red food colouring, if using, and set aside for 5 mins to allow any bubbles to burst. Make sure you go easy on the red food colouring, add a drop at a time for your preferred look.

Carefully pour the citrus mixture over the hot shortbread. Return the tin to the oven and bake for a further 25 mins until the topping has set.

Remove from the oven and allow to cool to room temperature, then cover and chill for at least 2 hrs to firm up. Scatter with desiccated coconut and cut into 16 squares or bars to serve.