A spur o' the moment recipe I'd like to share.
Remove excess paper from the garlic and onion. Drizzle both with olive oil, wrap in foil and bake in a 350 degree oven until soft and slightly browned. (Use a garlic baker if you've got one. I don't.) Mash the garlic and onion together with the olives. Salt to taste. Serve cold with bread.
Notes: I used cheap canned California olives, and it tasted fine. Taste before you add any salt. The amount of salt needed varies dramatically depending on how the olives are cured. The first time I made this I used a blender, which made the spread quite smooth and creamy, but I actually prefer it with a little more texture, so I recommend the mortar and pestle approach. All of the ingredients are pretty soft to begin with, so mashing by hand is no great hardship.