1 - 1 1/2cupsshredded (sharp!) cheddar cheeseor a mix of gruyere & cheddar
Break up the cauliflower head into bite-sized florets and set aside.
Add butter to a Dutch oven or pot over medium/low heat and cook, stirring every so often, until fully browned (4-6 minutes). Add heavy cream, mustard, garlic powder, black pepper, a generous pinch of salt and stir until combined. Add in the cauliflower bites, stir until evenly coated, cover with lid and simmer until softened but still retain a bite (10-15 minutes). Feel free to add a little extra salt now, keeping in mind you'll be adding the cheese still.
Make an arrowroot or konjac powder slurry (i.e. mix the powder with a couple tablespoons of cold water). Add it to the cauliflower mixture and stir until thickened (I've noticed various brands behave a little different, so just add it little by little to taste). Add in the cheese, stir until melted and serve right away!