Lightly crush the nigella seeds using a pestle and mortar to release their flavour.
Drain the chickpeas, reserving a small handful for garnish.
Add the remaining chickpeas to a blender along with the lemon juice, tahini, garlic and most of the crushed nigella seeds. Season with salt and pepper.
Blend until smooth, adding the cooking liquid or water a little at a time until you reach a thick, creamy consistency.
Taste and adjust seasoning if needed.
Transfer the hummus to a serving bowl. Top with the reserved chickpeas, a drizzle of olive oil and a sprinkle of the remaining nigella seeds. Add a pinch of chilli flakes if you like a little heat.
Serve with crudités, flatbread or falafels.