Preheat oven to 325°. Combine butter, sugar and egg; beat until thoroughly blended. Stir in flour and salt. Spread one-half of dough into 9 inch square pan. Bake 10 minutes; remove from oven. Spread jam to within 1/2 inch of edge. Add pistachios to remaining dough. Drop by spoonfuls over jam to cover. Bake 35 minutes until top is golden brown; cool. Cut into squares.