Preheat oven to 180°C.
Grease and line an 8" by 8" square tin with paper coming upto the rim. It will be easier to lift the brownie out of the tin.
In a bowl mix together sugar, melted butter and oil and whisk until well combined.
Add milk and vanilla and whisk until sugar starts melting.
Add in the flour, cocoa, baking powder and salt and whisk until the batter is nice and thick.
Transfer to the tin and smooth the top.
Bake in the preheated oven for 20 - 25 minutes.
Allow it to cool completely.
Cover with cling and refrigerate for 2 hours.
Remove the brownie from the tin, slice it up with a serrated knife to get perfect squares.
Allow it to come back to room temperature before serving.
Or MW until warm and serve it with a scoop of icecream.