140 g plain flour

a pinch of salt

140 g light brown muscovado sugar

90 g unsalted butter, chilled and diced

1 teaspoon baking powder

1 medium egg, beaten

3 tablespoons very strong espresso coffee, cold

1 tablespoon milk

60 g walnut pieces

one 20 cm square cake tin, greased and base-lined

Makes 16 squares

Sift the flour, salt and sugar into a mixing bowl. Add the cold chunks of butter and rub with your fingertips until the mixture resembles coarse crumbs. Set aside 4 tablespoons of the mixture. Add the baking powder to the rest and mix well.

Combine the egg, coffee and milk, then stir into the maxing bowl. When thoroughly combined, add 45 g of the nuts. Spoon the mixture into the tin and level it.

Mix the remaining nuts with the reserved crumbs and scatter over the top.

Bake in a preheated oven at 180°C (350°F) Gas 4 for about 20-25 minutes until golden brown and firm to the touch.

Let cool for about 1-2 minutes, then run a palette knife around the edges of the tin to loosen it and carefully turn on to a wire rack.

Leave until completely cold before cutting into 16 squares. Store in an airtight container and eat within 4 days, or freeze for to 1 month.