Shortbread: Preheat the oven to 350°F. Spray a 9-X-13-inch baking pan with pan spray and line with parchment paper. Spray the parchment.

In a large bowl cream the butter and sugar until fluffy. Gradually add the flour, ground rice and salt and allow the dough to come together. The dough will be crumbly but should hold together when you squeeze it.

Press the dough evenly into the bottom of the baking pan. Place in the oven and bake for 12 minutes. Rotate the pan from front to back and bake for another 10 minutes, until the shortbread is a deep golden brown. Remove from the oven and allow to cool on a rack to room temperature.

Caramel: Combine the sugar, golden syrup, water, and lemon juice in a large saucepan. Remove any sugar crystals from the sides of the pan by wiping down the sides with water. You can use your hand or a pastry brush. Place the pot on medium-high heat and bring to a boil. Wipe down any stray sugar crystals that appear using a very clean and wet pastry brush. Do not stir from this point on. Keep an eye on the pan. The mixture will be very bubbly.

When the sugar syrup starts to turn golden brown insert a candy thermometer to check the temperature. When it reaches 300°F, remove the pan from the heat and let it sit for 1minute, or until the bubbles subside. Carefully whisk in the heavy cream. Stir until smooth, then whisk in the condensed milk. Add the salt (vanilla salt is very nice here if you have it) Whisk until smooth.

Return the pan to the heat and stir constantly over medium heat until the caramel reaches 240°F. Remove from the heat and pour over the shortbread. While the caramel is warm sprinkle the surface with the best quality salt you have. Kosher is fine, Fleur de Sel is better, Maldon would be my preferred choice. Allow to set. This will take about 2 hours.

Melt the chocolate and butter over a bain marie or in the microwave. If using the microwave melt it slowly - in 30 second intervals. Stir well after each interval. Once completely melted pour over the caramel. Using an offset spatula, smooth the chocolate in a nice even layer.

Place in the refrigerator to set. They cut best when chilled. Cut into desired shape and size. Serve.