First, pour hot water over cashews. Set aside to soak.
Next, boil water for pasta.
Meanwhile, heat a large, deep skillet over medium heat. Add olive oil and onion along with a pinch of salt. Sauté onion until soft. About 5 minutes. Add garlic and sauté for one minute longer.
Scoop the onion and garlic mixture into a high speed blender. Next add the tomatoes, nutritional yeast. Then drain the cashews and add them to the blender.
Blend on high until the mixture is completely smooth and creamy, about one minute.
Add the pasta to the pasta water and cook until just BEFORE al dente as we will finish cooking in the sauce.
Pour the sauce back into the large, deep skillet. Turn heat to low. Add a pinch of salt, pepper and crushed red pepper. Simmer for 10 minutes while the pasta cooks.
Drain pasta and add it into the skillet with the sauce. Cook the pasta in the sauce for about 5 minutes, or until the pasta has finished cooking and has absorbed some of the sauce.
Garnish with basil, if desired and serve.