Preheat your oven to 350°F (175°C) and place the rack in the center position. Lightly butter or spray a 9x13-inch baking dish or casserole pan. This ensures the bars release easily once cooled.

In a mixing bowl, combine the yellow cake mix, 1 egg, and 1 stick of melted butter. Use an electric hand mixer for best results. The dough will be thick and sticky, similar to soft Play-Doh.

Scrape the mixture into the prepared pan. Using clean hands or a spatula, press the dough evenly into the bottom to form the crust. Set aside.

In the same mixing bowl (no need to wash it), beat the cream cheese until fluffy. Add the eggs and vanilla extract, beating until smooth.

Gradually add the powdered sugar with the mixer on low speed until fully incorporated. Then slowly pour in the melted butter and mix until smooth and creamy.

Stir in the entire bag of chocolate chips. The more chocolate, the better!

Pour the filling over the crust, spreading it evenly. Bake for 40–45 minutes, or until the edges are set but the center still looks slightly jiggly. That gooey center is what makes this dessert magical.

Let the bars cool for at least 2 hours before cutting. The filling needs time to set for clean slices. Cut into 12 large squares or up to 24 smaller ones.