Add all of the mushroom ingredients to a plastic bag, then allow to marinate for a few hours.
Preheat a skillet over medium-high heat then pan sear the mushrooms. Don't place them all in the pan if they don't fit. Keep them spaced apart so they sear and don't steam. You want a golden brown color on both sides. Set aside when finished.
In a blender whip up the avocado, garlic powder, avocado oil, lemon juice, basil, water, nutritional yeast, salt, and pepper. Add more water if necessary to thin out the sauce enough to blend, but don't overdo it because the zoodles will have some water as well.
Add the zucchini noodles to the pan and cook down until somewhat softened. Add the avocado sauce to the pan and heat through. Check the seasoning and adjust if needed.
Plate by adding all of the zoodles and sauce to a bowl. Top with mushrooms and basil leaves for garnish.