Preheat your oven to 325°F (165°C). Line two baking sheets with parchment paper or silicone baking mats.
In a clean mixing bowl, beat the egg whites with the cream of tartar and a pinch of salt using an electric mixer until stiff peaks form (about 3-5 minutes).
In a separate large bowl, whisk together the almond flour and powdered sugar.
Gently fold the beaten egg whites into the almond flour mixture, being careful not to deflate the egg whites too much. Stir in the almond extract until the dough is well combined.
Using your hands or a small cookie scoop, form the dough into 1-inch balls. Roll each ball in granulated sugar to coat it lightly. Place the cookies on the prepared baking sheets, spacing them about 1 inch apart.
If using, gently press a sliced almond into the top of each cookie for a decorative touch.
Bake for 15-18 minutes, or until the edges are lightly golden and the cookies are firm to the touch.
Allow the cookies to cool on the baking sheets for 5 minutes before transferring them to a wire rack to cool completely.
Enjoy these delicate, almond-flavored cookies with a cup of coffee or tea!