1 c. butter (or 1/2 butter, 1/2 butter)
7/8 c. sugar
1 tsp. ammonium carbonate dissolved in 1 tbsp. water
2 3/4 c. flour
1 tsp. vanilla

Melt and brown butter slightly. Remove to a cool place. Add sugar. Stir until cold, light and porous.

Add the dissolved ammonium carbonate (also called Baker's Ammonia available from drug stores or Scandinavian supply stores). Add flour and mix thoroughly.

Shape into small one inch balls. Bake at 300 degrees for about 30 minutes. Let cool thoroughly.

The ammonium carbonate evaporates completely, leaving a crackly surfaced cookie with a sandy texture.