What type of topping is used on apple crisp?

The topping used on apple crisp is streusel.

Streusel is a crumbly mixture usually made from flour, butter, and sugar. It is scattered over the apples before baking, where the butter helps create a crisp, browned topping while the fruit softens underneath. Many recipes add oats, brown sugar, cinnamon, nutmeg, or chopped nuts.

Apple crisp is closely related to apple crumble. In American usage, “crisp” commonly refers to the oat-containing or crunchy version, while “crumble” is especially associated with British usage, although the terms overlap and recipes are not rigidly standardized.

The dessert is not the same as apple pie because it normally has no rolled pastry crust enclosing the filling. It is also different from a cobbler, whose topping may be biscuit dough, batter, or another cake-like covering. Fondant, ganache, and meringue can appear on other desserts, but they are not the characteristic topping of apple crisp.

The dish is relatively modern in print: the earliest known reference to apple crisp dates to 1924. Its simpler crumb topping also made it a practical alternative to pastry-based apple desserts.