Preheat oven to 160oC

Line tin with baking paper

Whisk the butter (melted and hot), oil and sugar in a large bowl

Add the eggs and vanilla extract then whisk for a further minute

Gradually sift in the flour, cocoa powder, baking powder and salt, folding each ingredient into the batter until just combined (do not overmix)

Break up and mix in 200g of the white chocolate and then pour the batter into the prepared tin and bake for 20mins until the brownie centre no longer jiggles and a skewer is dirty but not wet

Remove from oven but keep in tray to continue baking until the brownies have cooled (at least 45mins)

Divide into portions and decorate with 100g melted white chocolate. Leave for a further 30mins then brownies are ready to eat or store in an airtight container for up to 1week