Step 1

Preheat oven to 350F and line a 9x9 inch baking dish with parchment paper or foil.

Step 2

Cream the butter then add the sugar, salt and beat until light and fluffy. Add the vanilla and egg yolk then mix until combined. Add the flour in a few batches and mix until just combined.

Step 3

Transfer to your prepared pan and press into an even layer then bake at 350F for about 22 minutes or until the edges are golden.

Step 4

While the base bakes make the caramel. This is easiest with a candy thermometer but you don't need one. Combine the butter, brown sugar, salt, vanilla, sweetened condensed milk and either golden syrup or corn syrup.

Step 5

Place over medium heat and whisk until melted and combined then continue whisking over the heat while the caramel bubbles and dakens to a richer color. Once it reaches 225F you'll see it starts to thicken and pull away from the edge, 5-6 minutes, your caramel is ready.

Step 6

Pour onto the shortbread base, smooth to the edges creating a flat layer. Chill for about 10 minutes so the caramel sets.

Step 7

Chop chocolate and melt with cream either in a double boiler or be microwaving in 2-3 20 second bursts, stirring in between. Pour the chocolate over the caramel and smooth into an even layer. Sprinkle with salt if desired then chill and cut into pieces.