In baking and pastry making, streusel (German pronunciation: [ˈʃtʁɔʏzəl]) is a crumbly topping of flour, butter, and sugar that is baked on top of muffins, breads, pies, and cakes. Some modern recipes add spices and chopped nutmeats. The mixture can also be layered or ribboned in the middle of the cake.Some dishes which have a streusel topping are streuselkuchen, coffee cake, and apple crisp.The term is also sometimes used for rich pastries topped with, or mixed with, streusel.