Preheat the oven to 350°F (175°C) and grease a 9x13 inch baking pan.

In a medium bowl, combine the yellow cake mix, 1/2 cup melted butter, and 1 egg. Mix until a thick dough forms.

Press the dough mixture firmly and evenly into the bottom of the prepared 9x13 inch pan to form the crust.

In a large bowl, beat the softened cream cheese until smooth and creamy using an electric mixer.

Add the 2 eggs and vanilla extract to the cream cheese and beat until well combined.

Add the second 1/2 cup of melted butter and continue to beat until smooth.

Gradually add the powdered sugar on low speed, then increase to medium and beat until the filling is light and fluffy.

Spread the cream cheese filling evenly over the top of the cake dough in the pan.

Bake for 35 to 45 minutes until the edges are golden brown and the center remains slightly jiggly.

Remove from the oven and allow the cake to cool completely in the pan to set before slicing into squares.