Toast the hazelnuts in the oven until golden brown and fragrant, about 10 minutes, checking often. Remove the skins from the nuts by rubbing them in a towel while they are still hot. Grind in food processor until they are powdered.
In a saucepan, combine the flour, milk, egg yolks, 6 ounces of the sugar, and the salt. Place the saucepan over medium heat, and cook until the mixture pulls away from the sides of the pan.
Melt the white chocolate in the top of a double boiler. Add the melted chocolate to the flour mixture and stir well. Set the mixture aside to cool and rest.
Melt the butter. Brush the inside of 4 (2-ounce) souffle molds with the melted butter. Sprinkle some sugar inside the molds and tap out the excess to leave a light coating of sugar all around the inside of the mold.
Whip the egg whites to soft peaks. Gently fold the egg white into the chocolate mixture, alternating with the hazelnut powder. Place the souffle mixture into the prepared molds. Bake for 18 minutes. Serve immediately.