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 150g of chocolate into the bowl and allow it to melt, then set aside to cool slightly.
Meanwhile, sieve the flour and cocoa powder into a large bowl, then stir in the sugar and a pinch of salt. Halve the vanilla pod lengthways, scrape out the seeds, then add them to the bowl. Stir in the oil, soya milk and melted chocolate until combined.
Roughly chop and stir in the remaining chocolate and most of the pecans, reserving a few for the top. Pour the mixture into the prepared tin, spreading it out evenly. Sprinkle over the remaining pecans, then place into the hot oven for 20 to 25 minutes, or until cooked on the outside, but still gooey in the middle.
Leave to cool for around 5 minutes, turn out onto a wire cooling rack, then serve warm with a scoop of vanilla ice cream, if you’re feeling extra indulgent.