Preheat your oven to 190°C and grease and line a 20cm square baking tray with baking paper.
Melt your dairy free butter (I usually do this in a saucepan on the hob) and then whisk together your hot melted butter and granulated sugar until combined.
Add your soy milk and vanilla extract and continue to whisk for a couple more minutes.
In a separate bowl combine your flour, baking powder, cocoa powder, xanthan gum and salt.
Add your dry ingredients to the wet ingredients and mix well.
Fold in your dairy free chocolate chips and then pour the batter into your lined baking tray. Press your oreos into the top and then bake in the oven for between 25-30 minutes.
Remove from the oven and leave to cool completely (if you cut the brownies when they are still hot they will fall apart slightly). I prefer to put my brownies in the fridge for a few hours once cool to completely solidify and then remove from the fridge and cut into squares.