Preheat the oven to 400°. Chop up your cauliflower head into small pieces and divide into two.
Toss half of the cauliflower with olive oil and roast on a baking sheet in the oven for 20-25 minutes, until they start to crisp up.
Steam the other half on the stove with 2 tbsp butter until the stems become tender. Reserve the water incase you need it in the next step.
In a food processor or blender, puree the steamed cauliflower and roasted cauliflower until smooth. Add some of the reserved water if the cauliflower is too thick. Here you can add in some heavy cream for a creamier consistency. Season with salt & pepper. Melt the remaining butter and mix it into the cauliflower mash. Enjoy!