Preheat the oven to 180ºC
Grease your baking tin and line it with parchment paper.
Sift your flour, baking soda, baking powder and salt in a bowl, and keep it aside.
Melt the butter in a saucepan and remove it off the gas once melted.
Whisk in the sugar, using a whisk, until the sugar is well combined.
Once this has cooled down a bit, add in the egg and the vanilla essence and mix until well combined. If you want a crackly top, whisk for a longer time.
Switch to a spatula and add the flour mixture in 2 batches, to avoid any lumps, and mix until just combined.
Stir in the white chocolate chunks and spoon this batter into the prepared tin.
Using a spoon, or your spatula, even it out.
Bake for 35-40 minutes, at 180ºC.
Leave it to cool for at least 15 minutes before cutting.
Once cut, it can be stored in an airtight container for upto 5 days.
