• Leave the ice cream out to soften enough to be spreadable.
• Add the sandwich cookies to a food processor, process until just crumbs remain.
• Add the melted butter, process to combine.
• Press into the bottom of a 10-inch springform pan.
• In a microwave-safe bowl add the chocolate chips and stout, microwave on high for 30 seconds, stir and repeat until well combined (this can also be done in the top of a double boiler.
• Pour half of the mixture in an even layer over the crust. Freeze until set.
• Add 1 ½ pints of ice cream over the chocolate, smooth into an even layer.
• Add the remaining chocolate mixture, top with mini chocolate peanut butter cups, freeze until set.
• Add the remaining ice cream, smooth into an even layer.
• Add the heavy cream, powdered sugar, and vanilla extract to the bowl of a stand mixer beat on high until well combined. Smooth over the top of the last ice cream layer. Freeze until ready to serve.

Make the caramel sauce for serving:

• 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.
• Allow the cake to sit at room temperature for about ten minutes to soften enough to cut.
• Drizzle with caramel before serving.