Preheat over to 400 degrees and toss 1/4 of the florets with olive oil, 1/2 tsp salt and pepper. Place on an oven sheet and roast about 20 minutes, or till nicely browned.

Combine remaining cauliflower with milk, salt, and pepper in a large saucepan with a lid. Heat on medium heat until simmering, then cover and cook about 20 minutes until cauliflower is tender. Drain cauliflower, but reserve the hot milk.

Add roasted cauliflower to a blender and pulse till mashed. Add the milk steamed cauliflower and pulse till smooth. Season with salt and pepper to taste. Guy says you can add half of the milk to the mixture, but I found I didn't need to add any. You have some reserved if you need it!