Preheat oven to 450°F.
In small bowl, soak dates in ½ cup hot water for 15 minutes; drain. Chop dates and using side of chef’s knife, work into a paste. Scrape into a bowl; stir in butter, garlic, salt, allspice, cumin, turmeric and cinnamon.
In a large skillet, place cauliflower stem-side down; spread butter mixture overtop, covering florets. Roast until lightly charred and fork-tender, about 50 to 60 minutes.
Meanwhile, gather the accompaniments. In a small bowl, combine onion, lemon juice and ¼ tsp of the salt. Let stand. In another bowl, stir together yogourt, garlic and the remaining ¼ tsp salt; set aside.
To serve, warm flatbread. Top cauliflower with onion mixture, green chilies, almonds, feta and sesame seeds.
Arrange flatbread and cilantro around cauliflower and serve with garlicky yogourt.