• Begin by preheating the oven to 180 C or 350 F and grease a 20x30 cm (9x13) inch pan with butter, then line it with parchment paper, to ensure minimal sticking.

To make the shortbread layer:

• Combine the softened butter, brown sugar, salt and vanilla extract, mixing till creamy. You can use an electric mixer to do this, but I like to use a wooden spoon. If the butter is soft, this is very easy to do with your hands instead of a machine.
• Gradually add in the flour, until you're left with a thick mass.
• press around three-quarters of the mixture onto the prepared pan to cover the entirety of the base, and very slightly up the sides, reserving the remaining mixture for the topping (this reserved quantity should equal around a cup).
• Bake for about 13-15 minutes or until the edges are just beginning to brown, then set aside and let the crust cool while you prepare the filling. 

To make the chocolate layer:

• To a large, microwave-safe bowl, add the chocolate, sweetened condensed milk, instant espresso powder and salt.
• Microwave the mixture stirring every 30 seconds or so, or until smooth. It should be quite thick.
• If you don't have a microwave, place the bowl over a small pot of hot water on the stovetop, making sure the bowl does not touch the water (a double boiler), then stir until completely melted.
• Spread the chocolate layer over the shortbread, as evenly as possible.

For the topping:

• Sprinkle atop the nuts and chocolate, distributing them as evenly as possible.
• Crumble the remaining shortbread dough that you had set aside in Step 4, as evenly as possible.
• Finally, drizzle atop the raspberry jam. I like to stir it slightly before drizzling so that it loosens up a bit.
• Bake the bars at 180 C for 35-40 minutes, or until you can see that shortbread on the top beginning to brown, the let it cool completely, it will take an hour or so. I actually like to chill these overnight in the fridge. That ensures nice, clean cuts, so if you need to transport these the chilling makes them a bit more solid. 
• Gently remove the parchment from the dish, peeling it from the edges, and cut into small squares. A little goes a long way over here- these are rather decadent.