Preheat oven to 350˚F.
Cream butter and sugar until light and fluffy. Add corn syrup, vanilla and salt; blend thoroughly. Add eggs one at a time, beating well after each addition. Stir in melted chocolate and walnuts. Fold in flour.
Pour into a greased 8-inch square pan. Bake for 22 to 26 minutes or until edges begin to pull away from the pan. When cool, cut into squares.