Preheat oven to 350 degrees. Grease a shallow 9 inch square cake pan with butter and line with parchment paper.
Place the 1/2 cup butter, flour and sugar in a food processor and process until it starts to bind together. Press into the prepared pan and level the top. Bake for 20-25 minutes, or till golden in color.
Meanwhile, make the filling. Place the butter, corn syrup and condensed milk in a heavy bottomed saucepan and heat gently until the sugar dissolves. Bring to a boil and then reduce heat and let simmer for 6 to 8 minutes, stirring until very thick. Pour over the shortbread and let chill in the fridge for 2 hours or till firm.
Melt the chocolate in a heat proof bowl over simmering water and stir until melted. Let cool slightly and then spread over the caramel. Let chill in the fridge for 2 hours or until set. Cut into 12 pieces. For "just a bite" goodies, cut each of the 12 slices into 2 or 3s.