Step 1

Heat the oven to 350°F with racks in the upper- and lower-middle positions. Line 2 baking sheets with kitchen parchment. In a liquid measuring cup or small bowl, whisk the whole egg, yolks, vanilla, almond extract (if using) and orange zest.

Step 2

In a food processor, combine 160 grams (¾ cup) white sugar, 65 grams (½ cup) almonds and the brown sugar; process until finely ground, about 30 seconds. Add the flour, 1 teaspoon cinnamon, baking powder, baking soda and salt; process until well combined, about 10 seconds. Scatter in the butter, then pulse until it is in pea-sized bits, about 20 pulses. With the machine running, drizzle in the egg mixture and process until it forms large clumps (it will not come together into a single mass), 30 to 45 seconds.

Step 3

Transfer the dough to a large bowl. Add the remaining 65 grams (½ cup) almonds and the chocolate. Using your hands, gently knead in the bowl just until the dough comes together and the nuts and chocolate are evenly distributed. Turn the dough out onto the counter and form it into a ball, then divide in half. Using your hands, roll each portion into a 14-inch log, pressing in any bits that come loose. Place the logs, about 4 inches apart, on one of the prepared baking sheets. With your hands, flatten the logs until 1 inch thick and 2 inches wide.

Step 4

Bake on the lower rack until the dough has spread into flat, fissured loaves that are firm on the surface and appear dry in the cracks, 25 to 30 minutes. Cool on the baking sheet on a wire rack for 20 minutes; leave the oven on. Meanwhile, in a wide, shallow bowl or on a medium plate, stir together the remaining 54 grams (¼ cup) white sugar and the remaining 1 teaspoon cinnamon.

Step 5

Using a wide metal spatula, carefully transfer the still-warm loaves to a cutting board; reserve the baking sheet and its parchment. Using a serrated knife and a gentle sawing motion, cut each loaf on the diagonal into ½-inch slices. Dredge the cut sides of each cookie in the cinnamon sugar, pressing so the sugar adheres (the cinnamon sugar will adhere better if the cookies are warm), then place them sugared side up on the baking sheets, dividing them between both baking sheets.

Step 6

Place both baking sheets in the oven and bake until the cookies are firm and dry, about 15 minutes, flipping each cookie and also rotating the baking sheets and switching their positions halfway through. Let cool on the baking sheets on wire racks for about 10 minutes. Transfer the mandelbrot directly to the racks and cool completely.