Preheat the oven to 350°F (180°C).
Sift the flour and cocoa into a mixing bowl and then add the white sugar, baking powder, salt and instant coffee powder and mix together.
Add the shredded zucchini, oil and vanilla and mix. The batter will look much too dry at this point and like it won't come together. Leave the bowl to sit for a couple of minutes while you prepare your baking tray.
Spray a 9x13 quarter sheet pan with non-stick spray and set aside.
Return to your mixing bowl and stir again, the zucchini should have released a little bit more moistness into the bowl and it should come together now into a thick batter. Transfer the batter to the baking pan and use the back of a spoon to press it down and smooth it out so that it reaches all the corners and is evenly spread out across the baking pan.
Bake for 30 minutes. Remove from the oven and leave to cool.
While the brownies are cooling, prepare your chocolate fudge topping.
Melt the vegan butter in a saucepan and then add the sugar and soy milk. Stir constantly until it reaches a full boil. When I say full boil I mean it will start foaming up as it boils (use a big enough pot to allow for this to happen). When it's reached a full boil remove from the heat and add in the chocolate chips and stir furiously until they have melted completely and it's a thick chocolate sauce. It will start to want to set once the chocolate is melted in so work quickly.
Pour it immediately over the top of the still warm brownies and leave to set.
Once the topping has set cut your brownies into squares and enjoy.