A puffy, muffin-size bread with a crisp brown crust and a somewhat hollow, moist interior. Basic popovers begin with a simple batter of eggs, milk, butter and flour. The high proportion of liquid in the batter creates steam that leavens the bread. Popovers may be baked in muffin tins or special popover pans, which have extra-deep cups. The name is said to come from the fact that as the batter bakes and expands, it pops over the sides of the cup-shaped indentations. Popovers can be plain or variously flavored with items such as cheese, spices or herbs.