Bring a large pot of water to a boil. Add cauliflower florets and cook until tender, 10 minutes. Drain well, pressing with paper towels or a clean dish towel to remove as much excess water as possible.
Transfer cauliflower to a food processor. Add garlic, salt, pepper, olive oil, butter, and parmesan cheese.
Secure the lid on the food processor. Pulse the cauliflower mixture until there are no lumps and it’s smooth like mashed potatoes. This may take a few minutes.
