Combine egg yolks, sugar, salt, and liqueur in a 3-quart pan. When sugar is dissolved, add milk. Cook in double boiler over medium heat until custard is thick enough to coat a spoon, stirring occasionally. Remove from heat and cool to room temperature; add cream and vanilla. Chill thoroughly. Pour mixture into ice cream freezer and freeze for 10 minutes or until mixture is very stiff. Add Oregon hazelnut crunch and process an additional 10 minutes or until desired consistency.
