Heat oven to 350°. In a bowl, stir together flour, finely ground pistachios and salt. In another bowl, beat butter and sugar for 2 minutes, until fluffy. Beat in egg. Pour in dry mixture and beat until just combined.
Shape level tablespoonfuls of dough into 21/2-inch logs and bend into crescents. Place on a baking sheet 2 inches apart. Bake at 350° for 14 to 16 minutes, until lightly browned. Remove to a wire rack to cool completely.
Melt chocolate per package directions. Dip crescents halfway into chocolate, allowing excess to drip off. Sprinkle with chopped pistachios. Place on parchment paper to dry.
