Elephant garlic is, indeed, delicious roasted, but it has a milder flavor than regular garlic. Personally, I wouldn't substitute.

Make that the leek family.

Elephant garlic is not actually garlic. I believe it's a member of the lily family although it's marketed as garlic. It does have a milder flavor.

Elephant garlic...yum...it's less powerful. Roast it with a drizzle of olive oil and scoop the softened cloves onto a baguette...the best.