Preheat oven to 325°F. Grease a 9 x 13-inch baking pan or spray with nonstick cooking spray. Set aside.
In a large bowl, stir together the dry cake mix, 1 egg, and melted butter until a soft dough comes together.
Press the mixture in an even layer in the prepared pan.
In a separate bowl, use an electric mixer on medium speed to beat together the cream cheese, the remaining 2 eggs, and the confectioners’ sugar until smooth, about 2-3 minutes.
Pour the cream cheese mixture over the crust and spread in an even layer. Bake for 30-40 minutes, until golden brown and set, but still a little bit “gooey” in the center.
Cool in the pan, and then dust with additional powdered sugar before slicing and serving.
Top with berries or whipped cream, if desired.