Preheat your oven to 350ºF. Liberally prepare a 9 × 13-inch baking pan with the nonstick method of your choice. (I recommend the parchment method described on p. 95.)
In a large bowl, whisk together all the ingredients until combined and thick. Evenly pat the batter into the bottom of the prepared pan.
For the Gooey Top Layer:
In the bowl of your stand mixer fitted with the whisk attachment, beat the eggs, sugar, cream cheese, vanilla extract, and salt over low speed. Once the sugar is fully incorporated, turn your mixer speed to high. Continue beating until all ingredients are well blended.
Pour the batter into the prepared pan, on top of the bottom layer, and spread it evenly across the pan using a spatula. Bake for 30 to 35 minutes. The center should still be gooey and will look underbaked.
Let cool for 10 to 15 minutes. Serve in the pan at room temperature.
Make sure your cream cheese is completely at room temperature in order to make sure that the top custard layer is smooth and lump free.