Preheat oven to 180C/350F and grease and line an 8x8 inch square pan.

Place the butter and brown sugar into a medium sized saucepan and melt over a low heat, stirring occasionally.

Once melted, leave to cool for 5-10 minutes. Once the mixture has cooled a little, tip it into a large bowl and add in the eggs and vanilla.

Stir until well combined and smooth.

Add in the baking powder, cinnamon and ginger and stir until combined.

Add in the flour and fold until just combined.

Spread half of the batter into your greased pan and smooth over.

Place the cookie butter into a small heatproof bowl and microwave for 15-20 seconds. Spoon half of the cookie butter onto the blondie batter and, using a skewer, swirl the cookie butter into the batter.

Sprinkle half of the white chocolate chunks on top of the cookie butter.

Spread the rest of the blondie batter over the white chocolate and then the rest of the cookie butter. Swirl the two together and finish off with a final sprinkle of white chocolate chunks.

Place in the oven for 25-30 minutes* until slightly risen and an inserted skewer into the centre comes out with a few crumbs on. (Be sure to get the blondie batter, rather than the cookie butter when you check!)

Leave to cool in the pan completely.

Once cooled, remove from pan and slice into 12-16 bars. Bars will keep in an airtight container, at room temperature for 4 days.