Cut cauliflower into florets. Place on rimmed baking sheet along with garlic cloves with their skins still on. Drizzle with oil, half the salt and remaining spices. Toss to evenly coat. Roast for 25-30 minutes, until cauliflower is tender when pierced with a fork.
Put roasted cauliflower plus tahini, lemon juice and water in bowl of food processor. Squeeze pulp form roasted garlic out of skins and into processor. Process until smooth and creamy, scraping down sides a few times.
If hummus is too thick, add additional water, one tablespoon at a time and process again.
Taste for seasoning, adding additional lemon or a pinch of red pepper flakes as desired.
Notes
STORE: Cool completely and store in an airtight container in the fridge for a week. If hummus has thickened too much while in the fridge, whisk in a tablespoon of water or lemon juice.