Add the butter to a saucepan. Cook over medium heat, stirring often, until it smells nutty and is a slight amber color, be careful not to burn it. Transfer the butter to the bowl of a stand mixer allow to cool for 15 to 20 minutes. Heat the oven to 325°F.

Add the sugar, vanilla, salt, and flour, mix on low speed until just combined.

Line an 8x8 pan with parchment.

Press the dough into the pan in an even layer.

Bake for 30 minutes or until the edges just start to brown. Remove from oven, allow to cool.

Add the sugar, cream of tartar, and water to a large heavy-bottom saucepan, stir until the sugar is dissolved, stop stirring.

Boil until a dark amber, about 8 minutes, swirling the pan occasionally if hot spots develop.

Remove from heat, stir in the butter until melted.

Slowly stir in the heavy cream and then the salt.

Pour in an even layer over the shortbread, chill until set, about 10 minutes.

Add the chocolate chips, beer, and espresso powder to a large microwave-safe bowl. Microwave on high for 30 seconds, stir and repeat until melted. Pour over the caramel in an even layer. Chill until set. Cut into squares to serve.