Place cashews in a bowl and cover with water. Allow them to soak for at least 2 hours or overnight. (I bring water to a boil in a tea kettle, cover the cashews with the hot water, and let them soak for 30 minutes when I’m in a hurry.)
Preheat oven to 375F. Slice spaghetti squash in half. Scoop out seeds and stringy flesh with a spoon. Rub a teaspoon of olive oil over each half (inside, not outside). Rub with garlic and sprinkle with salt and pepper.
Place face down on a baking sheet and bake for 35 minutes.
Meanwhile, place the sauce ingredients in a blender and blend until completely smooth and creamy. Set aside.
Use a fork to shred the spaghetti squash into strands. Heat a pan over medium heat. Place squash in a pan and cover with sauce (I used about 2/3 of the sauce and saved the rest). Toss to combine until warmed through.
Top with fresh basil and red pepper flakes prior to serving.