Preheat oven to 350°F.
Combine flour, and sugar. Chop butter into ½-inch pieces and cut in with pastry blender until mixture is crumbly. Add egg and mix just until evenly moistened.
Press dough into a 9½-inch tart pan, covering the bottom and sides. Line pan with foil, fill with pie weights or dried beans, and bake 20 minutes. Remove pie weights and cool.
In a heavy 2-quart saucepan over medium heat, melt butter and stir in sugar, corn syrup and condensed milk. Stirring to keep from scorching let mixture come to a boil and continue to cook until mixture turns a golden brown (245°F). Remove from heat, cool 15 minutes, and then stir in eggs.
Sprinkle chocolate in tart shell, cover with caramel sauce, and sprinkle nuts evenly over the top. Bake until center is set, 20-25 minutes. Cool before slicing into wedges for serving.
Makes about 12-16 servings.