Popovers begin with essentially the same batter as Yorkshire pudding. Purists will tell you that what makes Yorkshire pudding so great is that it’s cooked in beef drippings. But butter isn’t a bad stand-in, and popovers are pretty easy. You can buy special popover pans, with deeper, narrower cups which force the tops up in a more pronounced fashion, but I wouldn’t bother. Any muffin pan will produce a perfect popover if the butter is hot, the batter is rich and smooth and the baker is…