Macaroni penguin been considered separate species, but the close similarities of their DNA sequences has led some, such as the Australian ornithologists Les Christidis and Walter Boles, to treat the royal as a subspecies of the macaroni. The two species are very similar in appearance; the royal penguin has a white face instead of the usually black face of the macaroni. Interbreeding with the Indo-Pacific subspecies of the southern rockhopper penguin ("E. chrysocome filholi") has been reported at Heard and Marion Islands, with three hybrids recorded there by a 1987–88 Australian National Antarctic Research Expedition. The macaroni penguin is a large, crested
Macaroni and cheese while "shells and cheese" is sometimes used when it is made with Conchiglie. While Cheddar cheese is most commonly used for macaroni and cheese, other cheeses may also be used—usually sharp in flavor—and two or more cheeses can be combined. Popular recipes include using Gruyere, Gouda, Havarti, and Parmesan cheese. Macaroni and cheese can be made by simply layering slices of cheese and pasta (often with butter and/or evaporated milk) then baking in a casserole, rather than preparing as a cheese sauce. Also, some like to include a crunchy topping to their baked macaroni and cheese by topping it off