Prepare the baking dish

• Line a square baking dish with baking paper and set aside.
• Preheat the oven to 180 °C.

Mix the wet ingredients

• Whisk the melted butter with the brown sugar and granulated sugar until smooth.
• Beat in the egg and vanilla extract until combined.

Add the dry ingredients

• Stir in the flour, baking soda and salt until just combined.
• Fold in the crushed Oreo cookies.

Bake the cookie bars

• Spread the dough evenly in the prepared baking dish.
• Bake until golden and set in the centre.

Decorate and cut

• Let the cookie slab cool completely in the dish.
• Drizzle with the melted white chocolate and scatter over a few extra crushed Oreos.
• Cut into bars and serve.