Add a steamer insert or steamer basket to a large pot and fill the pot with water just under the seamer. Place it over high heat on the stove.
Wash and prepare the cauliflower by breaking the florets into medium-sized pieces. Try to make sure all the pieces are a similar size so they steam evenly.
Add the cauliflower to the steamer, along with the garlic. Add the lid and let the cauliflower steam until soft (about 7-10 minutes).
Remove the cauliflower and the garlic cloves from the pot and add them to your food processor while hot.
Add the sour cream, Parmesan, salt and pepper (to taste) and process on low speed just until the mixture becomes creamy. You may have to scrape down the inside of the bowl of the food processor to ensure everything is incorporated evenly and there are no chunks of cauliflower left.
Add the cauliflower mash to a bowl and garnish with the butter (let it melt over the hot cauliflower mash) along with some sea salt and pepper (if desired).
Serve alongside all your favourite dishes in place of mashed potatoes.