Bring a large pot of water to a boil. Fit the pot with a steamer attachment. Steam the cauliflower till fork tender (about 10 minutes). If you're preparing the cauliflower Alfredo spinach pasta, reserve the boiling water.
To prepare the cauliflower Alfredo sauce, add the cooked cauliflower, milk, nutritional yeast, miso, lemon juice, nut/seed butter, hemp hearts, or cashews, garlic, and sea salt to a powerful blender. Blend till smooth. Taste and add freshly ground black pepper or crushed red pepper to your liking.
To prepare the pasta: remove the steamer attachment from the boiling water once the cauliflower is ready. Salt the water. Add the pasta and cook according to package instructions. In the last 3 minutes of cooking time, add the spinach or kale to the pasta and simmering water.
Drain the pasta and greens and return them to the pot. Add the blended cauliflower Alfredo sauce. Mix everything and adjust salt as needed; add freshly ground black pepper to taste. Serve, topped with cashew parmesan if desired.