I came up with these sandwich cookies to add to the cookie tins I put together for holiday gifts this year--I wanted something bright to balance out the dark chocolate and spice cookies I had already included, and also something a little bit special. They turned out to be the unanimous favorite.
I was lucky enough to stumble on some bergamot oranges just as I was dreaming these up, and the mild, floral flavor of the marmalade they made worked beautifully in this cookie. But unless you care to track down some bergamots, regular oranges are perfectly fine, and will still make a delicious cookie. If you want something a little more special, you might try blood oranges, or even Meyer lemons.
The cookie recipe is adapted from one of my favorites: Martha Stewart's Rosemary Butter cookies. I added a little fennel to the mix and turned them into cut-out cookies. —Marguerite Preston
Cut the oranges into eighths lengthwise and remove the seeds and the white pith, then slice these wedges as thinly a possible.
Place sliced oranges in a small saucepan, cover with water and bring to a boil. Let boil for 5 minutes, then drain. (This step of blanching helps remove some of the bitterness and keep the bright color of the oranges. You can skip it if you like.)
Return oranges to the saucepan and add the sugar, cup of water, and salt. Bring to a boil and cook until the marmalade begins to set, about 30 minutes. You can test for doneness by dabbing a little onto a plate that's been left in the freezer. After five minutes, run your finger through the dab of marmalade: if it wrinkles up, it's ready; if not, continue cooking.
Remove marmalade from the heat and let cool completely. (Marmalade can be made several days in advance. Keep in the refrigerator until needed)
Using an electric mixer, beat butter and sugar on medium speed until pale and fluffy, about 2 minutes.
Mix in egg and vanilla until fully incorporated.
Add flour, salt, rosemary and fennel and mix until combined, scraping down the sides of the bowl as necessary.
Divide dough in half, shape into disks, wrap in plastic and refrigerate until firm, at least 1 hour.
Preheat oven to 375 F. Remove one disk from the fridge, and lightly dust the countertop and the dough with confectioner's sugar. Roll out dough to about 1/8" thickness. Cut out cookies using a 2" round cutter (or any shape you like). Cut a hole in the center of half the cookies using a second, smaller cutters. Gather and re-roll scraps. Repeat with second disk.
Place cookies about 1/2" apart on baking sheets lined with parchment paper. Bake for 10-15 minutes, until the edges are golden, rotating the baking sheets halfway through. Transfer baked cookies to a rack and let cool completely.
Spread a thin layer of marmalade on each round cookie and sandwich it with a ring cookie.