Brunost was invented in a Norwegian valley called Gudbrandsdalen in the 1860s by a farmer's daughter called Anne Hov. To make it, you boil up the whey - the leftover watery liquid from making normal cheese - until the natural milk sugars slowly turn brown and caramelise. Then it sets into a firm, fudgy block.
Because the milk sugars caramelise, brunost tastes a bit sweet, almost like a fudge with a slight cheesy tang. It is unlike any cheese in the rest of the world. Visitors to Norway often try it and don't know what to make of it.
Brunost is so famous in Norway that it comes with its own special tool: the 'ostehøvel', or cheese slicer. It is a thin metal wedge with a slot in it. Norwegians invented it in 1925 because brunost is too soft and sticky to slice with a knife. Today, the cheese slicer is used all over the world.
On a typical Norwegian breakfast, you'll see open slices of bread with butter, brunost shaved on top, and sometimes a spoonful of strawberry jam. It is also brilliant melted over a waffle, with a little blob of cream.