"Here in Seattle, there's a place called 60th Street Desserts that makes fabulous lemon shortbread bars; the cookies are both sweet and tart," says Lucille van der Hagen of Seattle, WA. "Could you ask Joan Williams, the owner, for the recipe?"
A crumb topping makes a nice addition to the classic bar cookie. Prepare the filling while the crust is baking; if the crust cools before the lemon filling is poured over it, the filling might seep beneath the crust.