01 - If cashews are not already soaked, boil them in water for 10 minutes. Drain and set aside.
02 - Boil the pasta in salted water until al dente as per package directions. Reserve 1/2 cup of pasta water before draining.
03 - In a blender, combine soaked cashews, water, nutritional yeast, lemon juice, garlic, Dijon mustard, salt, and black pepper. Blend until the mixture is completely smooth and creamy.
04 - Heat olive oil in a large skillet over medium heat. Sauté onion until translucent, about 3 minutes. Add cherry tomatoes and cook until softened, about 2 minutes. Stir in spinach and cook until wilted, around 1 minute.
05 - Add drained pasta and cashew sauce to the skillet with sautéed vegetables if using. Toss gently to coat, adding reserved pasta water gradually until the sauce reaches desired consistency.
06 - Taste for seasoning adjustments, then serve immediately. Garnish with additional black pepper or fresh herbs as preferred.