Method
Mix ground pistachios with 3/4 cup sugar and almond extract. In a separate bowl, whip egg whites until stiff, then gradually beat in salt and the remaining 1/4 cup sugar. Fold in the pistachio-sugar mixture with a wire whip.
Line cookie sheets with baking parchment. Spoon batter into pastry bag fitted with a 1/2" plain, round tip then press walnut-sized portions 1" apart onto parchment.
If you don't have a pastry bag, just portion out heaping spoonfuls of batter. Sprinkle lightly with chopped pistachios. Let cookies air dry on pans for 2 hours then bake at 300 degrees for 30 minutes.
Cookies should get lightly browned on bases, with the tops dry but the centers still chewy. Partially cool, then release cookies from parchment. Sift powdered sugar over if desired.
Makes about 40 cookies.