This is the mashed cauliflower of your dreams that people will prefer to potatoes. How? By cooking it beyond any point that seems reasonable or sane.
Microwave the cauliflower while covered in a heavy microwave-safe dish with a tight fitting lid for 10 minutes on high.
Remove the lid and stir the cauliflower. Microwave the cauliflower for 6 minutes on high with the lid removed.
You want to see the cauliflower starting to caramelize a little bit around the thin parts of the floret stems. Keep putting it back in the microwave for two minutes at a time uncovered until you do. Remove and let cool for 10 minutes.
Add the slightly cooled florets to a food processor and process until the whole thing begins to bind up just a little bit. Then scrape down the bowl, add a splash of half and half, and repeat until you reach the consistency of mashed potatoes. It should be just loose enough to process, but that's it. It takes about a 1/4 cup for me, but your results may be different.
Salt and pepper to taste, processing after each addition for about a minute to allow the salt to incorporate.
Serve with cheddar cheese gravy and sprinked with parsley.