Preheat oven to 350 degrees F. Line a 9x13 baking pan with parchment paper.
For the shortbread, put the flour, sugar, and salt in a food processor. Pulse once, and then add the butter. Pulse until crumbly.
Press this mixture evenly into the prepared pan. Bake for 10 minutes. Remove.
To make the brownies, put the butter and chocolate in a microwave safe bowl and melt in 20 second intervals, stirring each time.
When melted, add the sugar. Let cool for 5 minutes and add the eggs one at a time. Stir in the vanilla.
Combine the flour, cocoa, espresso, salt, and almonds and add those to the wet mixture. Stir well.
Pour this mixture overtop the shortbread and bake until the center is no longer jiggly and the edges start to pull away from the side of the pan. Cool completely before serving, and sprinkle with salt if desired.