Cook the chickpeas. Drain the soaked chickpeas and cover with fresh cold water by 3 inches. Bring to a boil, reduce to a gentle simmer, cook 60 to 90 minutes until completely tender. They should crush between two fingers with zero resistance. Do not salt the water until the last 10 minutes of cooking. Reserve 1 cup of cooking liquid before draining. Set aside a handful of whole cooked chickpeas for the garnish. If using canned, drain and rinse, warm in a small saucepan for 5 minutes, reserve half a cup of the warming water.
Pound -- do not blend. Work the chickpeas while they are still hot. Use a large mortar and pestle or a heavy bowl and a potato masher. Pound firmly until a coarse thick paste forms. If you use a food processor, pulse in short bursts only. Never run it continuously. The manuscript is clear. Thick, not runny.
Build the paste. Add the tahini, lemon juice, crushed garlic, and salt to the pounded chickpeas. Work everything together firmly. Add reserved cooking liquid one tablespoon at a time only if the paste feels too stiff to spread. Taste and adjust salt and lemon.
Plate -- the exact 1250 CE method. Wide flat plate, not a bowl. Spread the hummus flat to the edges with a slight well in the center. Garnish in this order. Drizzle olive oil generously across the entire surface. Scatter the chopped parsley. Scatter the chopped pistachios. Dust lightly with Ceylon cinnamon. Crush the rose buds between your fingers and scatter them across the top. Arrange the reserved whole chickpeas across the surface. The manuscript notes the dish will look quite nice. It is correct.