Preheat your oven to 350 degrees F. and grease a 9x13 inch baking dish with butter or nonstick cooking spray.
In a large mixing bowl, whisk together the cake mix, eggs, milk, vanilla, and melted butter until homogenous. Pour the cake batter into the baking dish and set aside.
Create your custard by whisking the cream cheese, milk, pudding mix, and egg together in a medium sized bowl. The custard does not need to be perfectly smooth, but should not have any large clumps in it.
Pour the custard over the cake batter and use a knife to swirl the two layers together.
Bake the cake for 40-45 minutes? Or until the edges are golden brown.
Allow your cake to cool for 30 minutes on the counter before slicing. Dust the top of the cake with powdered sugar, serve, and enjoy!
Notes
Because of the custard layer it can be tricky to know when this cake is done cooking. Once the edges are golden brown you can take your cake out of the oven. You can also poke around the edges with a toothpick. The center of the cake will have the most custard and will not result in a clean toothpick no matter how long you bake the cake.
Allowing your cake time to cool helps the custard settle, which allows you to get cleaner slices. If you try to cut and serve your cake immediately then you may end up scooping your cake rather than slicing it.
Room temperature cream cheese will be easier than cold cream cheese to mix in to the custard.
If you don’t have whole milk you can use half and half or 2% milk.
Salted butter helps balance the sweetness of the cake and custard. If you only have unsalted butter then you will want to add a teaspoon of salt to the cake batter.
It is not necessary to dust your cake with powdered sugar but it gives the cake a nicer look.
Store your leftover cake in the fridge for up to 4 days. This cake is great served warm, cold, or room temperature. If you’d like you can zap a leftover slice in the microwave for about 45 seconds.