For the cookies
1 cup (120 g) finely ground blanched almond flour
1 1/2 cups (180 g) tapioca starch/flour, plus more for sprinkling
1/2 teaspoon xanthan gum (optional)
1/2 teaspoon baking powder
1/2 teaspoon kosher salt
1/2 cup + 2 tablespoons (125 g) granulated sugar
4 tablespoons (56 g) unsalted butter, melted and cooled
1 egg (50 g, weighed out of shell) at room temperature, beaten
1 teaspoon pure vanilla extract
Water by the half-teaspoonful as necessary
For the chocolate glaze
6 ounces dark chocolate, chopped
3 tablespoons (42 g) virgin coconut oil
3 tablespoons (63 g) corn syrup
Coarse salt, for sprinkling (optional)
Preheat your oven to 325°F. Line rimmed baking sheets with unbleached parchment paper and set them aside.
In a large bowl, place the almond flour, tapioca starch, xanthan gum, baking powder, salt, and granulated sugar and whisk to combine well. Add the butter, egg, and vanilla, and mix to combine. If the dough has any spots that seem very dry, add water by the half-teaspoonful and mix to combine. Using clean hands, knead the dough together until it forms a ball. It will be thick and relatively stiff. Divide the dough in half and set one half aside, draped with a tea towel to prevent it from drying out.
Place the first half of the dough on a lightly floured surface, sprinkle the top lightly with more tapioca flour, and roll it out a bit less than 1/3-inch thick. Move the dough often to prevent it from sticking, sprinkling lightly with more tapioca flour as necessary. Using a 2 1/2-inch round cookie cutter, cut out rounds of dough and pull off the excess cookie dough around the rounds. Place the rounds of dough about 1-inch apart from one another on the prepared baking sheets. Gather and reroll the scraps, and repeat the process with all of the remaining dough until it’s all been used.
One at a time, place the baking sheets in the center of the preheated oven and bake until just set in the center (about 10 minutes). The edges of some of the cookies may brown slightly, but take them out before there is any significant browning. Remove the cookies from the oven and allow them to cool until set.
When the cookies are nearly cool, make the glaze. In a small, heat-safe bowl, place the chopped chocolate. Melt it in the microwave in 30-second bursts (stirring in between) or over a small simmering pot of water until melted and smooth. Add the coconut oil, and mix to combine. The mixture will be quite thin. Then, add the corn syrup and mix to combine. The mixture will thicken a bit after you add the corn syrup. Spoon the glaze on top of each cooled cookie and spread into an even layer, leaving a 1/4-inch border clean on the top of each cookie. Sprinkle the cookies lightly with coarse salt, if you like. Allow the glaze to set at room temperature or in the refrigerator before serving.