Chocolate cookies - Penny Melville-Brown

Ingredients

• 6oz/170g butter, softened
• 7oz/200g caster or soft brown sugar
• 1 teaspoon vanilla extract or paste
• 2eggs, one whole and the yolk only of the other, beaten
• 9oz/250g plain flour
• ½ teaspoon bicarbonate of soda
• ½ teaspoon salt
• 7oz/200g chocolate nibs