Heat the oven to 180C/160C fan/gas 4. Spread the cereal (we used malted wheats) out over a baking tray and toast in the oven for 8-10 mins until fragrant. Tip into a bowl and leave to cool.

Beat the unsalted butter, brown sugar and caster sugar together using an electric whisk or in a stand mixer for 5 mins until light and fluffy. Mix in the vanilla extract, a pinch of salt and the egg. Add the bicarbonate of soda, plain flour, chocolate and most of the toasted cereal, and mix until just combined.

Shape into 12 balls and arrange, well spaced apart, over two baking trays lined with baking parchment, then flatten slightly. Sprinkle over the remaining cereal. Bake for 10-12 mins, leave to cool on the trays for 10 mins, then cool completely on a wire rack. Will keep in an airtight container for four days.