Preheat the oven to 180°C/356°F (without fan).
Line a baking tray with baking paper.
Cream the butter, icing sugar, vanilla extract and lemon zest until light and fluffy.
Mix in the flour and baking powder.
Next add the rolled oats, dried cranberries and white chocolate chips.
Mix everything together to form a dough.
Pinch off small pieces of dough and roll into small balls.
Place the balls of dough on the baking tray and flatten them slightly.
The biscuits will spread as they bake so leave some space between each piece of dough.
Bake for 8-10 minutes until lightly golden.
Remove the baking tray from the oven and leave the biscuits on the tray for 4-5 minutes before removing them to a wire rack to cool.