Soak 1 cup (150 grams) of cashews in water for at least 4 hours or overnight. Drain and rinse the cashews before using.
Use a spiralizer or a vegetable peeler to create zucchini noodles from 4 medium-sized zucchinis. Set the noodles aside.
In a blender, combine the soaked cashews, 1 cup (240 ml) of water, 3 cloves of minced garlic, 1/4 cup (60 ml) of lemon juice, 1/2 cup (40 grams) of nutritional yeast, 1 teaspoon of salt, and 1/2 teaspoon of black pepper. Blend until smooth and creamy.
In a large pan, heat 1 tablespoon of olive oil over medium heat. Add the zucchini noodles and cook for 3-4 minutes, stirring occasionally, until they are slightly softened but still have a bit of crunch.
Pour the cashew alfredo sauce over the zucchini noodles and gently toss to combine. Cook for an additional 2-3 minutes until the sauce is heated through.
Serve the cashew alfredo zucchini noodles hot, garnished with chopped fresh parsley and crushed red pepper flakes, if desired.