Make the cookie dough

• Whisk the melted butter with the brown sugar and caster sugar until smooth.
• Beat in the egg, egg yolk and vanilla extract until glossy.
• Fold in the flour, cornflour, baking soda and salt until a soft dough forms.

Add the chocolate

• Fold the chopped milk chocolate and most of the Kinder Bueno pieces into the dough, keeping some back for topping.

Chill the dough

• Divide the dough into balls, press a piece of Kinder Bueno into the centre of each and seal.
• Chill in the fridge so the cookies hold their shape.

Bake the cookies

• Place the dough balls on a lined baking tray, spaced apart, and top with the remaining Kinder Bueno.
• Bake at 180 °C until the edges are set and the centres are still soft.

Cool and serve

• Leave the cookies on the tray to firm up before moving them to a rack.