Preheat the oven to 180ºC/350ºF/gas 4. Grease a square baking tin (roughly 20cm) with a little oil, then line with greaseproof paper.
Place a heatproof bowl over a pan of simmering water, making sure the base doesn’t touch the water. Break 250g of chocolate into the bowl and allow it to melt, then set aside to cool slightly.
Sieve the flour and Wellness Lab powder into a large bowl, then stir in the sugar and salt. Add in the oil, soy milk and melted chocolate and stir until combined.
Pour the mixture into the prepared tin, spreading it out evenly.
Place into the hot oven for 20 to 25 minutes, or until cooked on the outside, but still gooey in the middle.
Remove from the oven, allow to cool for a few minutes and then place in the fridge for one hour.
Cut into 16 equal squares and devour