Bring a large pot of water to a boil. Add cauliflower florets and boil for 10 to 15 minutes, or until tender when pierced with a fork. Alternatively, steam the florets using a steamer basket or microwave.
Drain the cauliflower thoroughly, then transfer to a clean kitchen towel or layer of paper towels. Pat dry to remove excess moisture.
Add the cauliflower to a food processor. Process until mostly smooth.
Add butter, Parmesan cheese, cream cheese, garlic powder, kosher salt, and black pepper to the food processor. Process again until creamy and well blended. Scrape down the sides as needed.
Transfer the cauliflower mash to a serving bowl. Garnish with chopped chives before serving.