These Oreo blondies are incredible - bites of crisp Oreo encased in soft, vanilla dough. I've tested the recipe over and over again to make sure you'll get perfect chewy, soft, cookie-dough like blondies every time.
Cube the butter into a bowl and melt in the microwave or on the hob over a pan of water until just melted. Allow to cool until tepid but still liquid.
Add the soft brown sugar and mix through.
Beat in the eggs and vanilla.
Add the flour and baking powder and mix together until smooth - the batter may be quite liquid if the butter was warm, but that's fine.
Add 250g (8 3/4 oz) of the Oreos and all of the white chocolate chips. Fold together.
Spoon into a lined baking tray. Top with the remaining Oreos.
Bake for 24-26 minutes until firm at the edges and a little under in the centre - it will continue to set as it cools.
Allow to cool in the tin for 10 minutes, then carefully turn out onto a wire rack to cool completely. To do this, I find it easiest to grab a *light* board (important so you don't squash the blondies!). Put the board on top of the blondie tin, then hold the tin underneath and turn the whole thing upside down, allowing the blondie to drop onto the tray/board. Peel off the paper, then place the cooling rack on top of the blondies and, holding the board underneath, flip again so that the blondie sits safely on the rack.
Once completely cool, slide the blondies onto a serving board and slice in 24 squares (in a pattern of 4 by 6)