Separate the cloves and peel most the skin of them. It's ok to leave some skin on. I think it somehow makes the garlic oil taste better with a little skin in it.
Put the cloves into a mortar. Pound them to reduce them to a medium fine pulp. (A good task for an older toddler!)
Pour the oil into a small pot. Add the garlic mush. Turn the heat on medium low and let the garlic fry away slowly until light golden brown, stirring every now and then. Keep an eye on the garlic, once it starts to brown, as you don't want it to brown too much before you take it off the heat. It will cook some more as it cools. Let cool completely and store in the refrigerator in a tightly closing jar.