When ready, using a Vitamix or food processor, carefully pour in cauliflower pieces. Then add butter, cream, sour cream, garlic powder, and season with salt and pepper. Pulsing the Vitamix or food processor, mash the cauliflower into a firm purée. In the Vitamix, you will need to use the tamper to mash down the contents towards the blades. Open the lid and taste the mash, add grated cheese, close the lid and pulse a few more times to blend in the cheese. Add salt and pepper to taste one additional time, if needed. Cauliflower Mash is now ready to serve.