Step 1: Steam the cauliflower florets in a steamer basket over boiling water for 12-15 minutes, or until they are very tender when pierced with a fork.
Step 2: Drain the cooked cauliflower thoroughly and let it sit in the colander for 2 minutes to allow excess steam to escape, ensuring a thicker mash.
Step 3: Transfer the hot cauliflower to a food processor or a large bowl if using an immersion blender.
Step 4: Add the sour cream, butter, garlic powder, salt, and pepper to the cauliflower.
Step 5: Process or blend until the mashed cauliflower with sour cream reaches your desired level of smoothness.
Step 6: Taste and adjust seasoning, then serve immediately garnished with fresh chives if desired.