Preheat oven to 350 degrees F (180 degrees C). Line a 13x9-inch baking pan with foil and grease with butter.
In a bowl, whisk together flour, granulated sugar and salt until well combined. Using a pastry blender, a fork or your fingers, cut in butter until evenly combined. Mixture will resemble coarse crumbs and start to come together. Using the back of a spoon or your fingers, press crust evenly into bottom of prepared pan.
Bake in preheated 350 degree oven for 18 to 20 minutes or until lightly golden.
Break the chocolate bars into squares and cover the crust. When the squares have melted push down on them a bit to spread the chocolate. Let cool completely on a wire rack.
In a large saucepan, over medium heat, heat corn syrup and brown sugar, stirring constantly until brown sugar is completely dissolved. Bring to a boil. Boil for 2 minutes without stirring. Add butter and cream. Boil and stir for 1 minute. Remove pan from heat and stir in the nuts. Spread nut filling evenly over cooled crust.
Bake for 20 minutes. Let cool completely in baking pan on a wire rack.
Using foil, lift cooled bars from pan and place on a cutting board. Cut into small bars.