Love these cookies. When I make them, people always ask for the recipe. These are a hit for cookie exchanges because they are a departure from chocolate. I don't consider the orange/lemon icing optional. The slight tang these give the cookies is perfect.
Bake the bar base just a bit longer, and then bake the whole thing just a bit more after you ice it, and it is so awesome! We call it Sidney Crack, because it is my husband's favorite cookie! He can eat half the pan in a day, so make a double batch! Will freeze well too.
When I make this same recipe which I found in an old cookbook, I frost with what I call a browned butter frosting: I heat 1/4 to 1/2 cup of butter in small saucepan over med. heat (and watching it carefully!) until it is golden brown and then I quickly add small amount (3 Tbsp.?) of cold milk to stop the butter from darkening too much. Next, I add enough SIFTED powdered sugar until the butter/milk combination is either pourable or spreadable for the top of the STILL HOT bars (the amount of milk and powdered sugar are not specific). Everyone raves about the bars/frosting combination.
Made this for a church group tonight and it was a hit!!