In baking and pastry making, streusel (IPA: [ˈʃtʁɔʏzəl]) is a crumb topping of butter, flour, and sugar that is baked on top of muffins, breads, pies, and cakes (e.g. Streuselkuchen). Some modern recipes add spices and chopped nutmeats. Although the topping is of German origin, it is sometimes referred to as Danish or Swedish.
The term is also sometimes used for rich pastries topped with, or mixed with, streusel.
From German Streusel 'something scattered or sprinkled,' from the verb streuen, cognate with the English verb strew.