1 tsp baking powder
190²µ/6¾´Ç³ú caster sugar
450g/1lb icing sugar
170g/6oz self-raising flour
1 tsp vanilla bean paste or vanilla extract
60g/2¼oz cookies and cream biscuits, crushed into crumbs
50g/1¾oz cookies and cream biscuits, crushed into crumbs
120g/4¼oz unsalted butter, softened
275g/9¾oz unsalted butter, softened
3 free-range eggs
splash of milk
140g/5oz soured cream (or 5 tbsp milk)