The Bojon Gourmet

Make the cookie dough
22 Place the sugar and lemon zest in the bowl of stand mixer fitted with the paddle attachment (or in a large bowl), and rub with your fingertips to combine. This will bring out the oils in the zest and make the cookies extra flavorful. 
1 Add the butter and beat (or stir with a wooden spoon or electric egg beater) on medium speed until combined, about 1 minute. We don’t want to aerate the dough in this case as that will make the cookies spread more.
2 Scrape down the sides of the bowl and add the egg and vanilla. Beat on medium speed or stir to combine. The mixture will look curdled at this point, but it will come together once the flours are added.
3 Sift in the almond, sweet rice, and oat flours with the tapioca starch, baking powder, salt, and cinnamon. Beat on low speed until just combined, scraping down the sides of the bowl once or twice.
4 Divide the dough in half and shape each half into a ball. Flatten the balls into disks (the thinner you make them, the easier it will be to roll them out), wrap in beeswax wrap or plastic wrap, and chill until firm, at least 30-60 minutes and up to 3 days. Or freeze for longer storage.
Shape
6 Unwrap one of the dough rounds and place it on a piece of parchment paper dusted lightly with oat flour. If the dough has been chilled for a while, you may need to let it soften for 5-10 minutes to make it easier to roll.
7 Dust the top of the dough with oat flour, using a dry pastry brush to sweep away excess flour. Roll the dough into a large oval that’s ⅛-inch thick or a little thicker.
8 When the dough starts to stick to the parchment, dust the top with a little oat flour, place a piece of parchment on top of the dough, and flip the whole thing over, parchment and all. Carefully peel away the now top piece of parchment, dust the dough with more flour, and continue rolling, sweeping away excess flour with a dry pastry brush.
9 Cut the dough into shapes using cookie cutters or biscuit cutters. As you work, place the cuts as close together as you can to maximize the dough. I use biscuit cutters that are 2 ½-inches in diameter. Once you've cut out the larger shapes, use smaller cookie cutters or biscuit cutters to cut out a little peep-hole in half of the cookies. I use a biscuit cutter that's 1-inch in diameter for the holes. You can bake the little cut-outs if you like, or add them to the dough scraps to re-roll and make more full-size cookies. 
18 Gather up the dough scraps and save them to combine with the dough scraps from the next dough round. You can gently smush these together, chill them for 20 minutes, and roll this dough to make more cookies. Repeat the rolling/cutting process with the other dough round.
10 Transfer the cut-outs to a cookie sheet lined with parchment and chill while the oven preheats, 20-30 minutes.
Bake
11 Position a rack in the upper third of the oven and preheat to 350ºF.
13 Bake the cookies one pan at a time in the upper third of the oven until set and slightly golden around the edges, 10-16 minutes. Rotate the cookie sheet halfway through for even baking. Watch closely as they can go from baked to burnt within minutes.
14 Let the cookies cool on the cookie sheets or transfer to a cooling rack. 
Finish
19 Separate the cooled cookies into pairs with a solid bottom and cut-out top. Turn the bottoms upside-down so the flat side is facing up. Spread 1 scant teaspoon of jam on the bottom cookies, leaving a quarter-inch of space around the edges. 
21 Sprinkle the cut-out tops lightly with powdered sugar. Make sandwiches by placing the cut-out tops on their bottom pairs.
15 The cookies keep well, airtight at room temperature, for up to 3 days. They will be crisp when freshly made and will soften slightly as they sit. Refrigerate the cookies for longer storage, up to 1 week.