Add the cashews to a medium bowl and cover with water. Cover with plastic wrap and let soak, refrigerated, overnight.
Drain the cashews and set aside.
Heat the oil in a large nonstick skillet over medium heat. Add the onion and cook, stirring occasionally, until light golden, about 10 minutes. Add the garlic and cook until fragrant, about 1 minute.
Transfer the mixture to a high-powered blender. Add the cashews, vegetable broth, almond milk, nutritional yeast, lemon juice, nutmeg, 1 1/2 teaspoons salt and 1/4 teaspoon pepper. Blend until smooth and combined.
To serve, heat the Alfredo sauce in a large skillet and toss with your favorite pasta and a splash of pasta water.
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