Roast several garlic cloves with shells intact in a small pan on medium-high heat. When they are browned on both sides and soft, simply pop garlic out of shells and set aside.
Bring a big pot of water to a rolling boil. Add plenty of salt and a drizzle of olive oil. Add in spaghetti. Cook for around 8-10 minutes. Drain, but be sure to reserve around 4 cups of pasta water.
Sauté a bunch of thickly sliced mushrooms and spinach (remember it will shrink down substantially).
In a blender, throw in soaked cashews, reserved pasta water, roasted garlic, a little bit of lemon juice, around 1 cup of full fat coconut milk (can sub for other plant milk), and ⅓ cup of tapioca starch (can sub for cornstarch or flour). Blend on high until mixture is completely smooth.
Pour creamy mixture into a large saucepan, and whisk constantly on medium-high heat until it begins to thicken.
Add in mushrooms, spinach, and pasta. With tongs, make sure the spaghetti is evenly coated with sauce.
Serve and top with fresh cracked pepper and basil if desired.
