The great thing about roasting a quantity of alliums, is that as well as softening the harshness of raw garic in recipes, and intensifying the sweetness and flavour of onions, you can then freeze them for future recipes.
They are sooo versatile too! Roasted garlic is delicious in dips, mayonnaise, soups, butter (roasted garlic butter rubbed under the skin of a chicken before roasting - yum!), mashed potato, and many other things.
Roasted onion (halves) are equally as versatile - all of the above (chopped up for some of them, obviously), and also on the side of roast dinners, sausage and mash, and too many things to mention!
Cook in bulk to make the most of using the oven, and in order to freeze, squeeze out the garlic cloves first.