Begin by assembling all of your ingredients.
Wash the broccoli, break it into smaller florets and place it in a steamer. Steam cook for about 4 mins until it's begining to soften.
While the broccoli is steaming, spiralise the courgette into thin noodles.
Once the broccoli is cooked enough, place it in a food processor with the walnuts, garlic, nutritional yeast flakes, lemon juice and avocado. Pulse a few times until processed to a fine texture. Add a splash or 2 of water to loosen the pesto for ease of stirring with the courgetti.
Add the broccoli pesto mixture to the courgetti and combine together so that the pesto is mixed through. Season to taste and serve.