Zest the lemon. Be careful to just get the yellow zest and not the bitter white pith.
1 lemon zest
Grate the courgette/zucchini and pat it dry, squeezing it out a little bit, with a clean cloth to remove the excess moisture. (prevents a soggy cake!)
200 g courgette
Add the sugar to a large bowl, then scrunch the lemon zest into the sugar with your fingers. This releases the lemon oil into the sugar and makes the taste more intense.
225 g sugar, 1 lemon zest
Add the aquafaba, oil and vanilla essence to the sugar.
Whisk the oil, aquafaba, and sugar until the mixture is well combined, lighter, and noticeably thickened.
Fold in the flour and baking powder. Mix well to combine.
300 g plain flour, 3 teaspoon baking powder
Add the courgette and mix well.
200 g courgette
Pour the cake mix into the prepared baking tin, and spread it out to the corners.
Pop in the oven and bake for 30-35 mins. Test with a skewer to see if it is cooked through. If it comes out clean, it's ready to take out of the oven. If it comes out a little gooey, leave the cake in for another 5 mins. The cooking time will really depend on how large your tin is, so if you use a smaller tin, adjust the time to be a little longer.
Cool the cake in it's tin for 10 mins, then turn out onto a cake rack.
Meanwhile, whisk together the icing and lemon juice. Add more icing sugar if necessary, you want a thickish yet drizzable mix.
Juice half lemon, ½ cup icing sugar
Once cool, turn the cake onto a serving plate and drizzle with the icing. Add pistachios or other decorations as desired.
Notes
This cake keeps well for at least 5 days in an airtight container. Probably longer but it was gone before I could test it!