Preheat oven to 375F (190C).

In a large bowl, cream together the butter and sugar until light and fluffy.

Add the egg, almond extract, and ground almonds; mix until well combined.

In a separate bowl, combine the flour, baking powder, and salt.

Gradually add the dry ingredients to the butter-sugar mixture, mixing until just combined. Do not overmix.

Roll the dough into a log about 12 inches long.

Cut the log into 16 even pieces.

Roll each piece into a ball and flatten slightly.

Place the cookies on a baking tray.

Brush the cookies with egg wash.

Bake for 15 minutes, or until golden brown.