Melt ½ cup butter in the microwave, stirring every 30 seconds.
In a large mixing bowl, combine yellow cake mix, melted butter, egg, egg yolk, and vanilla. Use a spatula to mix until fully combined. You are making a crust, so it will be thick.
Place parchment paper in a baking dish. Empty cake mixture in the baking dish, and flatten along the entire bottom and up the sides.
Melt the rest of the butter (6 tbsp) in the microwave, stirring every 30 seconds
In a separate bowl, beat together cream cheese, melted butter, eggs, powdered sugar, vanilla, and salt. Beat for about 5 minutes to ensure there are no clumps in the mixture.
Pour mixture over the crust and spread until the entire crust is covered.
When ready to bake, preheat your oven to 350°F.
Bake for 40 minutes, or just until the edges are set. It will continue to set as they cool.
Allow the cake to cool in the pan for an hour before cutting. Sprinkle it with powdered sugar and enjoy with a scoop of ice cream and berries!