Arrange 1 rack in lower third of oven. Preheat oven to 350 degrees
In a medium sized heavy saucepan combine brown sugar, flour, and salt. Cook on medium heat, stirring well with a whisk. Stir in corn syrup and bring mix to a boil. Cook for 1 minute, stirring occasionally until sugar dissolves.
Remove pan from heat and add butter and chocolate-whisk until smooth. Cool to room temperature, then stir in nuts, vanilla and eggs
Fit pie dough into a 9 inch tart pan (with removable bottom)(note-I used a 10 inch and it was fine) coated with cooking spray, pressing dough into the bottom and up the sides. Spoon walnut mixture into prepared crust
Bake at 350 degrees for 33 minutes or until set. Cool for 20 minutes in pan on wire rack. Remove from tart pan, slide tart onto serving platter. Cut into wedges. Yield: 12 wedges