How to Make It
In a food processor, pulse the flour, almond meal, sugar and salt until combined. Add the butter and pulse until the mixture forms large clumps.
Turn the dough out onto a work surface and knead gently until it comes together. Divide the dough in half and press each half into a disk. Roll out each disk between 2 sheets of wax paper to 1/4 inch thick. Slide the wax paper–covered disks onto a baking sheet and freeze for at least 1 hour, until firm.
Preheat the oven to 350° and line 2 large baking sheets with parchment paper. Working with one piece of dough at a time, peel off the top sheet of wax paper. Using a 1 1/2-inch round cookie cutter, stamp out the cookies as close together as possible. Arrange the cookies 1 inch apart on the prepared baking sheets. Lightly brush the cookies with the egg and sprinkle with the black and white sesame seeds.
Bake the sesame cookies for 17 to 20 minutes, until they are lightly browned; shift the baking sheets from top to bottom and front to back halfway through. Let the cookies cool on the baking sheets for 3 minutes, then transfer them to a wire rack and let them cool completely.
The rolled-out frozen cookie dough can be wrapped in plastic and kept frozen for up to 2 weeks; thaw the dough slightly before using. The baked cookies can be kept in an airtight container at room temperature for up to 2 days.
Almond meal is available at health food stores and at many grocery stores. To make your own, process 4 1/2 ounces blanched almonds until finely ground.