Preheat oven to 170c fan. Grease and line a 10.5 inch (27cm) x 7 inch (17.5cm) x 1 tray bake tin or similar with baking parchment or greaseproof paper. Please note. If you use a tin with a different size, the baking times may differ.
Using an electric mixer, beat together the butter and sugar until soft, light and fluffy. This will only take a couple of mins.
Sift in the flour and baking powder. Add the Vanilla Extract, oats, glace ginger and white chocolate chips. Mix together until well combined and forms a dough. This will only take a few seconds when using the electric mixer. Do not over beat.
Press the dough into the prepared baking pan making sure the level is even.
Bake in the oven for 30 mins or until baked and lightly golden. Testing the centre of the bake with a skewer until it comes out clean.
Take out of the oven and dust with caster sugar if required. On this occasion I decided not to dust them. Leave in the tin to cool a little, before turning out onto a wire rack to cool completely before cutting into bars or slices. This will give you good clean bite sized cookie bars.
Notes
They will keep in an airtight tin for a couple of days.