In the bowl of a stand mixer fitted with the paddle attachment, combine the butter, sugar, and almond extract. Beat on medium until light, fluffy, and doubled in volume, 3 to 5 minutes, using a rubber spatula to scrape down the bottom and sides of the bowl as necessary. Reduce the mixer to low, add the egg, and beat until just incorporated. Scrape down the bottom and sides of the bowl.
With the mixer on low, gradually add the dry ingredients and beat until combined. Increase the mixer to medium-low and beat until the dough clumps around the paddle and/or sides of the bowl, 2 to 3 minutes.
Tip the dough out onto a piece of parchment paper around the size of a half sheet pan and use your hands to shape it into a roughly 6-inch square. Place a second sheet of parchment over the dough, creating a parchment sandwich with the dough in the middle. Use a rolling pin to flatten the dough between the parchment sheets, working from left to right. Turn the dough 90 degrees and repeat every so often—doing so will help prevent the dough from cracking as you roll it. If the parchment starts to wrinkle and leave creases in the cookie dough, pull the sheet loose and smooth it before rolling the dough more. Continue rotating and rolling until you have a rough oval about 13 inches wide, 18 inches long, and between ⅛ and ¼ inch thick.
Transfer the slab of cookie dough, still in between the parchment, to a half sheet pan. Freeze for at least 1 hour, or refrigerate overnight.
Position a rack in the center of the oven and preheat the oven to 350°F.
Remove the sheet pan of dough from the refrigerator. Use the overhanging parchment as handles to carefully lift the slab of dough off the sheet pan and onto the counter. Peel the top layer of parchment from the slab and use it to line the sheet pan once more. Line a second half sheet pan with parchment as well.
Use a cookie cutter to cut out shapes, placing the cookies at least 1 ½ inches apart on the prepared sheet pans. Use a second smaller cookie cutter to cut out smaller shapes from the center of half the cookies. The dough should still be cool and firm to the touch. If not, chill both sheet pans in the freezer for at least 10 minutes before baking.
Bake one pan at a time (keeping the other pan in the refrigerator) for 10 minutes, or until the cookies are golden brown around the edges. Cool the cookies on the pan on a wire rack for 20 minutes, or until the edges and bottoms of the cookies are set and feel firm to the touch. Repeat to bake the remaining cookies.
Once the cookies have cooled to room temperature, prepare them for assembly. Organize the cookies so that the cookies with the smaller cut-outs are all on one sheet pan. Garnish these cookies with confectioners’ sugar and/or cocoa powder.
Melt the white chocolate and tahini in the top of a double boiler or in a heatproof bowl set over a medium, heavy-bottomed saucepan filled with a few inches of simmering water (be sure the bottom of the bowl does not touch the water) over medium heat.
Let the filling cool in its pan or bowl on a wire rack for 15 to 20 minutes. Use an offset spatula to spread the filling over the bottom whole cookies; top with the cut-out cookies. Allow the cookies to “set” for about an hour or so; the chocolate will harden to room temperature and “glue” the cookies together. Once set, the cookies can be stored in an airtight container or zip-top bag at room temperature for up to 3 days.