Pre-heat oven to 180ºC.
Whisk together the eggs, yogurt, maple syrup and butter until smooth.
Slowly add the cocoa powder and flour until it forms into a batter.
Use your hands to squeeze the liquid from the courgette, then add to the batter stirring well to ensure it is fully combined.
Pour the mixture into a baking tin lined with parchment paper and bake in the oven for 30 minutes or until a skewer comes out clean. Then leave aside to cool.
To make the ganache, whip together all fo the ingredients until you have a smooth chocolate sauce.
Use a spatula to spread the ganache over the top of the brownie, and finally sprinkle over the nuts.
Cut into squares to serve.