Directions

1. Preheat the oven to 180°C/160°C fan/Gas 4. Line a 20cm (8in) square tin with baking paper.

2. In a mixing bowl, mix together the flour, cocoa powder and caster sugar.
3. Stir in the melted butter and vanilla
4. Spoon the mixture into the prepared tin and press down well with the back of a spoon.

5. Bake for 30 - 35 minutes until crusty at the edges. Sprinkle with the granulated sugar and leave to cool in the tin for 10 minutes.

6. Use the paper to lift the cracknel out of the tin. Cut into 9 squares and transfer to a wire rack to cool completely

7. To make the custard: mix the cornflour to a smooth paste with a little of the milk. Heat the remaining milk in a saucepan until almost boiling, then pour onto the cornflour paste. Return the milk to the pan and simmer, whisking, for 2 - 3 minutes until smooth and thick.

8. Remove from the heat and whisk in the butter and sugar, plus the chocolate or extract and colouring, depending on your choice of custard.
9. Serve with the chocolate cracknel.