Combine the cashews, broth, tomatoes, nutritional yeast, lemon juice, and garlic in a blender or food processor. Blend on high until the sauce is completely smooth. Stir in the basil and season with salt and pepper to taste.
Transfer the pasta to a large bowl and toss it with the alfredo sauce. If the sauce is too thick, add a tablespoon or two of cooking water from the pasta.
Notes
I'm sure store-bought sun-dried tomatoes would work in this too, but I haven't tried it myself. If the tomatoes you buy are especially dry, let them sit in warm water for a few minutes to plump them up.
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