Preheat the oven to 180°C / 356°F fan and line the base and sides of an approx. 19cm (7.5”) brownie tin with baking paper.
Add the chickpeas, peanut butter, maple syrup, olive oil, vanilla extract and 120ml (1/2 cup) of the plant-based milk to a food processor, then process until smooth.
Next add the cocoa powder, baking powder, bicarbonate of soda and ground almonds to the food processor, then process again until combined.
Carefully remove the blade from the food processor. Then finely chop 80g (2.8oz) of the chocolate and add it to the food processor, along with a pinch of salt. Stir to combine.
Pour the brownie batter into the lined tin and bake for 25-30 minutes.
Once the brownie has finished baking, remove it from the oven and leave to cool in the tin for 30 minutes.
Next, to make the ganache, roughly break up the remaining chocolate in your hands and add it to a small saucepan with the remaining plant-based milk. Stir regularly over a low heat until melted and silky smooth. Leave the ganache to one side to set a little.
Once the brownie has cooled, remove it from the tin. Then pour over the ganache and spread it out using a spoon. Note: if the ganache is too runny, leave it a little longer to go firm. You can either slice the brownie as it is or leave it for 30 minutes or so at room temperature until the ganache sets.
To serve, slice into 9 squares and sprinkle with salt, if you like.