Probably one of the best known types of cheese. Usually with blue veins inside the paste. The blue mould is usually Penicillium Roqueforti, but might also be a type called Penicillium Glaucum that you can find in Gorgonzola. Both these fungi are commonly found in nature.
Blue cheese can be from any type of milk, most common is ewe’s and cow’s milk though. Well know blue cheeses are Roquefort (France), Stilton and Stichelton (Britain), Gorgonszola (Italy) and Cabrales (Spain).
Color of veins vary from blue to green and grey depending on the cheese, but it is still called blue. The veins are formed through a process called «needling» to give the fungi air to «breathe» and subsequently grow. However, in France this type of cheese is also called Persille or Persillé, because the blue «veins» are rather resembling curly-leaf Parsley.