Put 1 in. water and 1 tsp. salt in a large pot with a steamer insert. Add squash; steam until tender but not falling apart, 8 to 10 minutes.
Cook butter in a small saucepan over medium-low heat, swirling, until it's golden and smells nutty, 3 to 4 minutes; set aside.
Season yogurt with 1/2 tsp. salt and spread on a very large platter or 8 plates. Arrange squash on top. Drizzle with 1 tbsp. cider molasses and the browned butter. Sprinkle with 2 tbsp. dukkah. Serve with flatbread and more cider molasses and dukkah to add at the table.
*Find pomegranate molasses at well-stocked grocery stores. Find dukkah at some gourmet grocery stores and worldspice.com, or make your own.