Preheat the oven to 180 C fan/200 C/400 F/gas mark 6. Grease 3 individual 10 x 7.5cm (4 x 2in) ramekins with coconut oil.
Sift the flour, icing sugar, cocoa powder, coffee, baking powder and bicarbonate of soda into a medium-sized bowl and mix to combine.
In a separate bowl, mash the banana, then add the milk, apple cider vinegar and vanilla bean paste. Whisk to combine.
Add the wet ingredients to the dry and fold together – don’t overmix! Divide half of the batter between the ramekins, then carefully press a third of the chocolate chunks into the centre of each ramekin. Spoon the remaining batter over the chocolate chunks until they are completely hidden. You don’t want to overfill them as the sponge will rise in the ramekins.
Place the ramekins on a baking tray and place the tray in the centre of the oven. Bake for 20–25 minutes. Once baked, carefully run a knife around the edge of each ramekin to help loosen the sponge.
Place a plate on top of each ramekin in turn, flip upside down, then lift off the ramekin. Serve the cakes with a dusting of cocoa powder, along with dairy-free cream, ice cream and fresh berries (optional). The chocolate will be runny while the sponge is hot, but will become less so as it cools, so these are best enjoyed straight from the oven.
Holly’s tip: If the cakes cool too much before serving, revive them by briefly warming them in the oven or microwave.