Preheat the oven to 325°F. Spray an 8-inch square baking pan with nonstick cooking spray.

In the bowl of an electric mixer fitted with the paddle attachment, combine the cream cheese, the 2 tablespoons of sugar, and vanilla, stirring until creamy and smooth. Separate one of the eggs, reserving the white for later use, and add the yolk to the cream cheese mixture. Stir to combine, then set aside.

In a small bowl, whisk together the flour, cocoa, baking powder, and salt; set aside.

In a medium saucepan, heat the oil and chocolate over medium heat, whisking until the chocolate is melted. Whisk in the remaining cup of sugar and stir until melted. Add the buttermilk, applesauce, and vanilla. Remove from the heat. Add the remaining whole egg and the reserved egg white, whisking constantly until incorporated to prevent the eggs from curdling. Add the reserved flour mixture, mixing until just combined. Transfer brownie batter to the prepared pan.

Using a tablespoon, drop 9 dollops of the cream cheese mixture on top of the brownie batter. Draw the tip of a sharp knife or skewer through the two batters in a criss-cross fashion to create a swirled effect.

Bake the brownies until the top is just firm to the touch, rotating halfway through baking, about 40 minutes. Let cool completely in the pan on a wire rack.

Coat a serrated knife with nonstick cooking spray and cut into 16 squares. Store in an airtight container in the refrigerator up to 3 days.