Preheat oven to 350°F. Line a 9x13 inch metal pan with nonstick foil or parchment paper.
In a mixing bowl, mix the flour, brown sugar and salt together thoroughly. Add softened butter and mix until uniformly crumbly; press evenly into pan and bake for 12 minutes.
While crust bakes, using the same mixing bowl, whisk together sugar, corn syrup, eggs, salt, 2 tablespoons melted butter, vanilla, cayenne and cinnamon. Stir in chocolate chunks and nuts.
Pour evenly over hot, partially baked crust. Continue baking for 25 to 30 minutes or until set. Cool completely, then chill thoroughly before lifting from pan and slicing.