Cook the pasta in boiling water according to package instructions, then drain and set aside. Save some (about a cup) of the pasta water for adding back in later.
Soak the cashews in boiling hot water for 5 minutes, then drain and add to a high powered blender, along with the milk, nutritional yeast, lemon juice and salt. Blend until very smooth.
To the blender, add the spinach and artichokes, and pulse a few times, using the tamper, being careful not to blend too much as you want to leave a good amount of texture. Set aside.
In the same pot you used to cook the pasta, add a tablespoon of olive oil over medium heat, then add the onion and garlic and sauté for 3-4 minutes until translucent.
Now add the creamy mixture from the blender, and stir, cooking for 2-3 minutes until it thickens somewhat. Be careful not to burn the bottom.
Now add the cooked pasta, and stir to mix. I usually add some of the water, 1/2 cup or more, if it's too thick. Serve immediately and enjoy!