Test the florets with a fork to make sure they are fall-apart tender. Then strain out the water and transfer to a blender. Add the garlic, 1 cup water, and 1.5 tsp of Vegetable Base. I like to use Better than Bouillon Vegetable Base. Blend until smooth.
Add the spinach and pulse until incorporated and starting to turn the sauce green, but so you can still see pieces of the spinach.
If you made the Cauliflower Cream Sauce a day or so ahead, warm it up now before adding it to the pasta.