Preheat oven to 350 degrees F. Prepare a 9x13 baking pan by spraying it with nonstick spray. Line with parchment paper for easy removal. Set aside.
Make the crust: To a large bowl, add yellow cake mix, melted butter, eggs, vanilla and salt. Stir together with a fork to create a dough.
15.25 ounce package yellow cake mix, ½ cup unsalted butter, 2 large eggs, ½ teaspoon vanilla extract, ¼ teaspoon salt
Press the mixture into the prepared baking pan to form a crust. Set aside.
Make the filling: Using a hand mixer and a large bowl or the bowl of your stand mixer fitted with a paddle attachment, add the cream cheese, eggs, melted butter, vanilla, and salt. Beat on medium speed until creamy.
8 ounce package cream cheese, 2 large eggs, ½ cup unsalted butter, 2 teaspoons vanilla extract, ½ teaspoon salt
Slowly add in powdered sugar, 1 cup at a time, until all has been incorporated.
4 cups sifted powdered sugar
Pour filling mixture on top of the crust in the pan.
Bake for about 35-45 minutes, or until the edges are lightly golden brown and the center still has a slight jiggle.
Cool completely before slicing and serving. Sprinkle powdered sugar over top.
Notes
Cake mix: Be sure that it's a 15 ounce cake mix. Some brands have started going to a 13 ounce mix. You can also make your own homemade cake mix.
Butter: If using salted butter, just add a pinch of salt in the crust and filling.
Cream cheese: I recommend using full-fat cream cheese in the recipe for the richest, creamiest filling.