Line baking trays with parchment paper or silicone baking mats. Preheat oven to 325 degrees Fahrenheit.

Beat egg in a small bowl. Set aside.

Cream butter and sugar in a large bowl until light and fluffy. Beat in all but 1 Tbsp of the beaten egg. Set the saved portion aside. Add the almond extract to the butter mixture. Mix to combine.

Combine the flour, baking soda and salt in a separate bowl. Add to butter mixture and mix to combine.

Scoop the cookie dough and round into balls (about 1½ Tbsp each). Place on prepared baking sheets, 2-inches apart. Flatten to ½-inch thick with the bottom of a drinking glass.

Gently press a single almond halfway into the center of each cookie dough ball. Add ½ tsp water to the saved beaten egg and whisk together. Brush the tops of the cookies with the egg mixture.