To toast the almond flour: Heat a large skillet over medium-low heat. Add the almond flour and stir constantly until it turns golden and becomes fragrant, 4 to 6 minutes. Remove the toasted almond flour from the heat and immediately transfer it to a medium bowl (this stops it from burning).  , To make the dough: To the bowl with the toasted almond flour, add the all-purpose (or gluten-free) flour, salt, and baking soda. Whisk together until well combined. Set aside.  , In a large bowl or the bowl of a stand mixer, beat together the butter and sugar on low speed until smooth, about 2 minutes. Beat in the egg and almond extract until combined; the butter may look slightly curdled at this stage, and that is OK. , Add the dry ingredients to the butter mixture and stir until it forms a soft, sticky dough.  , On plastic wrap or your favorite reusable wrap, form the dough into a roughly 8" x 8" square and wrap to seal. Refrigerate the dough until firm, about 2 hours. Do not skip this step; chilling the dough allows you to handle it successfully going forward. , To bake the cookies: Line two baking sheets with parchment or silicone liners. Remove the dough from the refrigerator and use a bowl scraper, bench knife, or a tablespoon scoop to divide it into 18 equal pieces (about 24g each). , Roll each piece of dough into a 1 to 1 1/2" ball and place all 18 dough balls onto one of the prepared baking sheets. (Arrange the cookies close together so that they fit on a single baking sheet, but aim to leave about 1" between the cookies, if possible; you’ll arrange them on two baking sheets before baking.) , Brush each dough ball with egg wash and place an almond in the center. Using the palm of your hand or the bottom of a drinking glass to flatten it to 3/4" thick (this keeps the almond in place). Place the baking sheet with the flattened cookies in the refrigerator, uncovered, for 10 to 15 minutes for the dough to firm up.    , Preheat oven to 350°F with a rack in the center position.  , Arrange 9 of the flattened cookies evenly on the other prepared baking sheet. Space out the remaining 9 flattened cookies and return the baking sheet to the refrigerator while you bake the first batch of cookies. , Bake the cookies for 17 to 18 minutes, or until the tops turn a light golden color. , Remove the cookies from the oven and let them cool for 5 minutes on the pan before transferring to a rack to cool completely.  , Repeat with the second baking sheet of cookies. , Storage instructions: Store Chinese almond cookies in an airtight container at room temperature for up to a week. Freeze for longer storage.