Preheat the oven to 350°F (180°C) and line a 9x9 inch baking dish with parchment paper or cooking spray.
Mix the chocolate chip cookie mix and semi-sweet chocolate chips using a rubber spatula.
Gently pour the melted butter and egg and stir until thoroughly mixed. The batter will feel slightly sticky.
Get your spatula wet and separate the dough in half. Press one-half of your prepared cookie dough into your baking dish in an even layer using your damp spatula. Lightly floured fingers can work for this, also! Set the pan aside for now.
To make the cheesecake filling for the bars, beat one package of softened cream cheese with a hand or stand mixer until light and creamy.
Turning your mixer down to a low setting, add in the powdered sugar and vanilla extract. Beat until thoroughly mixed.
Turn off your mixer, then gently incorporate the egg using your spatula. The cheesecake will initially seem runny; stir until it is smooth and shiny.
Pour the cheesecake batter over the prepared cookie dough layer in the baking dish. Smooth carefully with a spatula to ensure even coverage.
Using the remaining cookie dough, crumble small pieces in your hands and drop gently over the cheesecake layer.
Bake for 35 minutes or until the dough is cooked and the edges are golden brown.
Allow the bars to cool completely before cutting into squares and serving. Best eaten when chilled!