Preheat your oven to 400 degrees Fahrenheit. Spray two half-sheet pans liberally with non-stick spray. Wash and dry the garlic cloves.

Add the garlic cloves to a large bowl, then add the oil and toss to coat evenly. Add the salt and pepper and mix again.

Divide the garlic cloves evenly between the two pans, and spread them out. Cover the pans with foil, then prick the foil with a fork about 20 times per pan.

Put both pans in the oven for 30 minutes, switching the pans halfway through. Remove the foil, and roast an additional 5 to 15 minutes, until the garlic is golden brown. (Check the bottom side of several cloves to be sure they aren't getting too done as they brown faster than the tops.)

Let the pans cool completely, then use a spatula to loosen the garlic cloves. Put the pans in the freezer for at least an hour, then loosen the cloves again and transfer them to a Ziploc bag. 

Store in the freezer.