Dust Windowed Tops Before Filling to Keep Jam Glossy

On windowed sandwich biscuits like Linzer Augen, always dust the cut-out tops with icing sugar before you assemble them, never after. Dust after filling and the sugar lands on the exposed jam in each window, where it dissolves into the fruit and dulls the glossy "eye" that makes these biscuits sing. Dusting the tops first, then setting them onto the jam-spread bases, keeps the sugar crisp and white on the shortbread and the jam bright and mirror-like in the openings. Fill the windows with a little extra warm, sieved jam right at the end so each eye sits glossy and proud.