Steam cauliflower until tender, 6 minutes. Transfer to a food processor fitted with a metal blade. Add milk, 2 tablespoons oil, whole garlic clove, parsley, rosemary, salt and pepper and pulse until smooth.
In a large skillet, heat remaining oil over medium heat. Add minced garlic and cook 1 minute. Add spinach, season with salt and cook until just wilted, 2 minutes. Squeeze with lemon.
Divide cauliflower mash among four bowls and top with spinach, chicken and pomegranate seeds.