Place the flour, almond flour, sugar, and salt in the bowl of a food processor. Run for 30 seconds or until everything is well mixed.

Place butter cubes on top and run for 30 to 60 seconds or until all butter is incorporated. Note: it will not form a dough.

Turn mixture out onto a clean work surface and knead until you have a dough that sticks together, about a minute.

Place dough between two pieces of parchment and roll to a thickness of 1/4 inch. Place on a baking sheet and freeze for at least 1 hour.

Use a 1 1/2-inch cookie cutter to cut out as many cookies as possible, placing them on a baking sheet as you work. Re-roll and cut more cookies from the scraps. Place cookie rounds in the freezer for another 30 minutes.

Preheat oven to 350°F. Line baking sheets with silicone baking mats or parchment.

Brush cookies with egg, then sprinkle with sesame seeds, lightly pressing seeds to ensure they stick.

Transfer to prepared baking sheets, leaving an inch of space between cookies. Bake 20 minutes, or until lightly browned and golden.

Let cookies cool on the baking sheet for 10 minutes before transferring to a rack to cool completely.