Put a large pot of water on to boil.
If you are using, combine breadcrumbs, parsley and lemon zest in a small bowl. Set aside.
Next, add cauliflower and cashews to the boiling water; cook until the cauliflower is very tender, about 15 minutes. (Save the boiling water for the zoodles) Using a slotted spoon, transfer cauliflower and cashews to a blender.
Bring the pot of water back to a boil. Add zucchini; cook for one minute. Drain; rinse immediately with cold water to stop cooking.
Heat avocado oil in a large skillet over medium high heat. Add zucchini noodles and garlic; cook and stir until just tender, about 5 minutes. Season to taste with salt and pepper.
Add lemon juice, miso, onion powder, salt and 1 cup water to the blender; process until smooth. Add the sauce to the pasta and stir until well coated. Serve topped with the breadcrumb mixture.