A crunchy topping used to cover pies, fruit crisps and coffeecakes. It has a high proportion of butter and sugar to flour and can contain any kind of chopped nut, oats and spices.

The term streusel is from the German, for "something strewn together". It's a crumb topping of butter, flour, and various spices that is baked on top of muffins, breads, and cakes (eg. Streuselkuchen).