Preheat your oven to 350°F (175°C).
In a large bowl, mix the cake mix, melted butter, and egg until well combined.
Press the mixture into the bottom of a greased 9x13-inch baking pan.
In another bowl, beat the softened cream cheese until smooth.
Add in powdered sugar, eggs, and vanilla extract; mix until combined.
Pour the cream cheese mixture over the cake layer in the pan.
Bake for 40-45 minutes until the edges are golden but the center is still gooey.
Allow to cool for 10 minutes before slicing.
Dust with powdered sugar before serving.
Enjoy your delicious gooey butter cake!