01 - 
                You can keep these in a covered container in your fridge for three days, or pop them in the freezer for up to three months.
              
              
              
                02 - 
                Let the bars cool off at room temp, then chill for 4 hours in your fridge before you cut them up. Eat them cold.
              
              
              
                03 - 
                Bake them for 50 to 55 minutes, until the top isn't shiny and the edges start to brown a bit. Let cool on the counter.
              
              
              
                04 - 
                Pour the cream cheese mix carefully over the brownie layer. Grab a butter knife or a skewer and give it a good swirl for that marbled look.
              
              
              
                05 - 
                Use a different bowl. Beat the cream cheese and sour cream together until really smooth. Add in sugar, vanilla, and eggs, and beat until it all blends together.
              
              
              
                06 - 
                Scoop the brownie mixture into your lined pan and smooth it out. Set it aside for now.
              
              
              
                07 - 
                Stir sugar and cocoa into the melted chocolate-butter. Use a spoon. Add eggs and vanilla, stir, then add salt. Mix in flour at the end, just until barely blended. Don't overdo it.
              
              
              
                08 - 
                Toss the chocolate and butter into a big, microwave-friendly bowl. Heat for 30 seconds at a time, stirring each time, until smooth and melted. Should take about 2 minutes.
              
              
              
                09 - 
                Turn your oven on—175°C. Line a 23-by-23-cm pan with foil, then hit it with some nonstick spray.