Slice onion and caramelize in 1 tablespoon of butter over medium-low heat for about 15 minutes, stirring constantly to avoid burning. Once completely caramelized remove from the pan and set aside. I also threw in the three cloves of garlic towards the end to release some of their flavor.
Meanwhile, cut off the cauliflower stem and break into florets. Place in a casserole dish and fill with water until about 1/4 of the florets are covered. Microwave for 5-7 minutes, until they are soft.
Place cauliflower and 3 garlic cloves into a food processor (may need to do this in batches if your processor is not large enough) and process for a few minutes.
Over medium heat add 2-3 tablespoons of butter and stir constantly until just beginning to brown, about 3-4 minutes, don't let it burn!
Add 1/2 of the caramelized onions, browned butter, and a healthy pinch of salt and pepper to the cauliflower in the processor. Process and start adding in coconut milk until fully incorporated and a smooth, creamy mash has been formed. This may take several minutes depending on your food processor. Taste and adjust salt and pepper.