Preheat your oven to 350°F (175°C) for even baking.

In a medium bowl, combine 1 box of yellow cake mix, 1 stick of melted butter, and 1 egg. Mix until well combined. The dough will be thick and sticky.

Grease a 9x13 inch baking dish with butter or non-stick spray.

Gently press the dough into an even layer in the baking pan. Firmly pack it to create a solid base.

In a large bowl, beat 8 oz of softened cream cheese until smooth and creamy, about 1-2 minutes.

Add 2 beaten eggs to the cream cheese, whisking until well mixed and smooth.

Gradually add 3 1/2 cups of powdered sugar, whisking until the filling is thick and creamy.

Pour the cream cheese filling over the crust, using a spatula to spread it evenly.

Bake for 25-30 minutes, until the top is lightly golden and the center reaches 160°F on a food thermometer. The center may still jiggle slightly and will set as it cools.

Remove from the oven and let cool on a wire rack for 1-2 hours to allow the filling to set.

After cooling, cut into squares or rectangles with a sharp knife. Serve, and refrigerate any leftovers.