Preheat the oven to 325°F (160°C) and line a small baking tray with baking paper for immediate use.
In a medium bowl, thoroughly mix the almond flour, granulated sugar, powdered sugar (for the dough), and salt until evenly combined.
Add the egg whites, almond extract, and vanilla extract, then stir with a spatula until a thick, paste-like dough forms that holds its shape.
Prepare for rolling by placing the remaining powdered sugar (for rolling) in one small bowl and the sliced almonds in another.
Scoop the dough into 6 equal portions per tray (about 1 tablespoon each), roll lightly in powdered sugar, then gently press into the sliced almonds to coat.
Arrange the cookies on the prepared tray, spacing them about 2 inches (5 cm) apart, ensuring not to flatten them.
Bake for 14–16 minutes, until the tops are cracked and matte and the bottoms are just beginning to turn a pale golden brown.
Remove from the oven and let cool on the tray for 10 minutes before carefully transferring to a wire rack to cool completely.
Enjoy your delicious chewy almond cookies!