Prepare the Crust: Crush the Oreos into crumbs in a food processor. Add the butter and pulse several times until combined.
Line a 9x9inch baking pan with parchment. Press the Oreo crust mixture into the bottom of the pan. Freeze while you prepare the chocolate filling.
Chocolate Cream Layer: Add the chopped chocolate and 1 cup of heavy cream to a heat-proof bowl and use a double boiler method (place the bowl over a pot with about 1 inch of simmering water) and stir occasionally until the mixture is combined and smooth. Remove from the heat and stir in the espresso powder. Add in the vodka and khalua and stir until incorporated and smooth. This may take a minute to really get it combined and uniform. *Make sure not to wait until the ganache is too cool to do this or it may separate.
Allow the ganache to cool for about 15 minutes in the refrigerator.
Combine the remaining two cups of heavy cream with the sugar and vanilla. Beat on medium-high speed until stiff peaks start to form.
Gently fold the whipped cream into the cooled ganache until smooth and creamy and there are no streaks of chocolate. Pour this mixture into the cooled Oreo crust and spread evenly.
Chill for about 4-6 hours to allow to fully set.
Prepare the Espresso Mascarpone Whipped Cream: Once the chocolate layer has set, combine the Kahlua mascarpone whipped cream ingredients and beat until stiff peaks form. Spread over top of the set chocolate layer. Chill until ready to serve.
To serve, cut into squares and top with a cocoa powder dusting and espresso beans to garnish. This is super rich, so I cut into 16 small squares, but you can certainly make them larger. Chocolate covered espresso beans would be fun too!