Dice the cauliflower into florets. Add the florets to a pan of boiling water and simmer until tender. About 5 minutes. Drain the cauliflower and pat dry.
Add the cauliflower to a food processor along with the garlic, Parmesan and butter. Season to taste and blend to a mash.
Add the sour cream and blend again.
Transfer the mash to a serving dish and stir through the chives to serve.