Preheat oven to 325 F (160 C). In a medium bowl, whisk flour, and salt together. In a double boiler, melt chocolate chips. In a large metal bowl, beat softened butter, sugar, and chocolate together. Beat in eggs and vanilla. Using a wooden spoon, gradually stir in flour mixture until well combined. Chop roasted hazelnuts and fold into mixture. Roll into 1 1/2 inch (4 cm) balls leaving at least 1 inch (2.5 cm) between cookies. Flatten with the bottom of a jar or glass cup. Bake for 13 to 15 minutes. Let cool on a wire rack.