Spoon the hummus into a medium bowl (about 14 cm diameter) and smooth the top flat.
Pipe sour cream in 5 horizontal lines across the hummus surface, then run the bag across in the opposite direction to create a criss-cross bandage pattern.
Press two olive halves, cut side down, near the upper third of the hummus to form the mummy eyes.
Place the bowl in the centre of a large dark slate or board.
Arrange carrots, cucumber spears and cherry tomatoes in radiating clusters around the bowl.
Fill the remaining gaps with pita triangles and crackers.
Serve immediately. Hummus can sit at room temperature for up to 1 hour; refrigerate the board if assembling more than 1 hour ahead and bring it out 15 minutes before serving.