Remove outer leaves from cauliflower. Cut up the vegetable into florets and further coarsely chop the florets—core included. Omit this step if you use the packaged rice cauliflower.
Place the cauliflower in a high-speed blender or food processor with the plant milk or butter. Blend on high speed until pureed. You might need to puree a certain amount of cauliflower if your blender is not large enough to hold everything, and then add in and puree the rest of the florets (or rice cauliflower) in batches—set aside.
Cover the bottom of a large skillet with two tablespoons of olive oil and heat over medium heat. Add the garlic and the onions. Cook and stir for 3 minutes. Season with a few pinches of salt and pepper.
Transfer the sauteed garlic and onions to the blender containing the pureed cauliflower. Mix everything for a few seconds or until the sauteed veggies are completely blended in with the cauliflower.
Cover the same large skillet again with one tablespoon of olive oil and heat over the same medium heat.
Transfer the pureed veggies from the blender to the skillet, spreading it evenly over the bottom of the pan. Cook and stir frequently to avoid browning for at least 5 minutes or until the pureed cauliflower mix is fully cooked.
Season to taste with salt, pepper, and nutmeg.
When fully cooked, stir in the grated cheese until completely melted.
Garnish with fresh parsley leaves, chives, or extra grated cheese to taste (optional).