Place tahini in the bowl of your food processor and process for about one minute. Add garbanzo beans, a little at a time, and continue to process until smooth. Add a little bit of water as needed. If you need to do this in batches, you can remove the puréed beans and place them in a separate bowl until you have finished. Then add them all back to the processor before adding the garlic, lemon juice, lemon zest, spices, and olive oil. Blend all together until very smooth.
Remove the hummus to a serving bowl. Smooth the top with a spoon or rubber spatula. Using the back of a spoon, make a swirling pattern from the outside of the bowl towards the center. Cover and refrigerate until ready to serve.
When you are ready to serve, drizzle extra olive oil into the well you made with the spoon and arrange the garnishes on the remaining part of the hummus. Serve with pita bread, chips, or crudités.