Preheat the oven to 180oc/160oc fan and grease and line a square baking pan. Place a bowl over a simmering pan of water, taking care not to let the bowl touch the water and melt the butter in the bowl. Add the two sugars and melt together, stirring constantly for five minutes. Remove from the heat to cool for five minutes.
Whisk in the eggs then fold through the flour, salt and baking powder. Add the chopped oreos and chocolate chips and stir to combine then pour into the prepared tray. Bake for 30 minutes until the top is shiny and the middle soft then remove from the oven to cool completely in the tin. Lift out the tin and slice into 12 squares or thin bars.
Recipe by Victoria Sponge Pease Pudding at http://victoriaspongepeasepudding.com/baking/oreo-chocolate-chip-blondies/