I love the taste of roasted garlic but there is no way that I have time to add an extra hour to dinner prep during the busy school year by roasting garlic that day. Instead, I make a batch ahead of time and keep it in the freezer.
I usually buy a few sleeves of garlic when they are on sale. It is just as easy to roast 6 heads of garlic as it is 3.
The only ingredients that you need are olive oil and the garlic. Any herbs that you add are optional. They do create additional flavor, so you might want to include them.
I use what herbs I have on hand. I haven't come across a combination that I didn't like. Some of my favorite herbs to use are oregano, rosemary, and thyme. I use fresh herbs when I have them, but I didn't feel like walking out in the rain just to cut herbs. Dried herbs worked just fine.
Preheat oven to 350F
Cut the top third off of the garlic and place on a sheet of aluminum foil.
-- If I am making a big batch of garlic, I will use a pyrex dish and cover the top with aluminum foil
-- If I am only roasting a few heads of garlic, I will use a long enough piece of foil to fold over to form a "tent"
Drizzle the olive oil over the cut garlic. Place the herbs in the packet with the garlic. Don't stress about trying to keep the herbs on top of the cut garlic. It is all going to cook together and the flavors will mix.
Roast for 45-55 minutes. When the garlic is sufficiently roasted, it should easily slide out of the paper when you squeeze it and should be a "spreadable" consistency.
Garlic will stay fresh in your freezer for approximately three months
If you have successfully resisted the urge to spread the roasted garlic on a thick slice of focaccia or crusty bread, it is very easy to freeze to save for later.
The easiest way that I have found to freeze it is to put it in a re-sealable bag and flatten out the garlic. When you are ready to use it, you can break off the amount that you want to use. I also press indentations into the garlic. That makes it easier to break off when it is frozen. The flattened bag also takes up little room in your freezer.