This recipe is (barely) adapted from Everyday Food (http://www.marthastewart...). These cookies take a little bit of time to put together, but they’re well worth the effort. Adding a little bit of orange zest makes them even better. This recipe yields a lot of cookies, but any extras will keep well in an airtight container in the freezer. —Carey Nershi
Preheat oven to 325° F. Line two baking sheets with parchment or silpat mats. Combine flour and salt together and set aside.
Cream together butter and sugar in a large bowl. Add in whole eggs and egg white, then vanilla, and continue to beat on high until light and fluffy. Lower speed and gradually beat in flour mixture until just incorporated.
Transfer batter to a ziploc bag with a 1/2-inch hole snipped in one corner. Pipe batter into 2-inch long strips. Bake for 13–15 minutes, or until the edges of the cookies just begin to brown. Remove from oven and let cool on the baking sheet for 5 minutes, then transfer to cooling racks. Allow cookies to cool completely.
Arrange cookie halves in pairs of similar shape and size. Melt chocolate in a double boiler until smooth, then remove from heat and let cool for 10 minutes.
Spoon the chocolate onto one cookie half, and sprinkle on a pinch of orange zest. Gently press the other half on top until the chocolate just reaches the edges. Repeat with the remaining cookies and let the sandwiches sit until the chocolate has set.
Any extra cookies will keep well in an airtight container in the freezer.