Prepare the filling. Place the cream cheese, butter, sugar, egg and Kahlua in a large, mixing bowl and blend with an electric mixer on low speed, or with a wooden spoon, until the mixture is smooth and well combined. Set the bowl aside.

Place a rack in the center of the oven and preheat the oven to 350F. Lightly mist the bottom of a 13- by 9-inch pan with vegetable oil spray. Set the pan aside.

Place the brownie mix, oil, Kahlua, and eggs in a large mixing bowl. Stir with a wooden spoon until all the ingredients are incorporated and the batter lightens in texture, 50 strokes. Pour the batter into the prepared pan and spread it out evenly with a rubber spatula. Spread the cream cheese filling over the top of the batter, and using a dinner knife, swirl it into the batter to create a marbled effect. Scatter the chocolate chips evenly over the top if desired. Place the pan in the oven.

Bake the brownies until they are lightly browned and the outer 2 inches form a crust, 27 to 32 inches. Remove the pan from the oven and place it on a wire rack to cool for 30 minutes. Cut the brownies into 24 squares.

Store these brownies, covered with plastic wrap or aluminum foil, at room temperature for up to 3 days or in the refrigerator for up to 1 week. Or freeze them, wrapped in foil, for up to 6 months. Thaw the brownies overnight on the counter before serving.