If using dried chickpeas: soak the chickpeas overnight or for at least 6 hours. Rinse, add 2 cups of fresh water, and pressure cook until soft.
Preheat the oven to 180 C.
Remove the skin from the pumpkin and cut into approx 1 ½ inch cubes. Toss with 1 tablespoon of olive oil and salt, and spread out on a baking tray.
Halve the garlic head horizontally with the skin on. Wrap in aluminium foil and drizzle over ½ teaspoon of olive oil. Add to the baking tray along with the pumpkin.
Roast the pumpkin and garlic for 30-40 mins or until a knife inserted into a piece of pumpkin goes through without resistance. Set aside to cool slightly.
Toss the sesame seeds in a dry pan until lightly browned. Add to a blender jar. Squeeze out the garlic cloves with your hand and add to the jar.
Also add the chickpeas and pumpkin. Squeeze in lemon juice. Season with salt. Blend to a smooth purée adding ice cubes (instead of water) to adjust the consistency. Check and adjust seasoning. Dollop onto a plate.
Spiced butter: melt the butter in a small pan just until it starts to bubble up–about 30 seconds. Take the pan off the heat and add cumin seeds, coriander powder, chilli powder, and salt.
Swirl the spices in the butter for a few seconds. Spoon the butter over the hummus, sprinkle over sesame seeds and serve.