Bar cookies are baked in rectangular or square pans. Flavors are bold, with generous measures of chocolate, nuts, lemon and other citrus fruits. The batter is often soft enough to pour or spread with a spatula, though it can also be so crumbly that it must be pressed in an even layer. A pastry base may be added to hold a rich filling, as with Austrian hazelnut Linzer bars.
The texture of finished cookies varies, from moist American date-nut bars, to chewy British oatmeal flapjacks. Generally, the thinner the layer of batter the crisper the cookie will be, so it is important to use the pan size specified. Bar cookies may be baked in multi-colored layers, marbled, or sandwiched like small cakes and coated with glaze, icing or butter cream.