This classic St. Louis pastry was supposedly made by accident, when a baker reversed the amount of butter and flour in a recipe. But unlike many mistakes, this was a happy one, resulting in an iconic, indulgent dessert.
Preheat oven to 350 degrees F.
Lightly grease a 9-by-13-inch cake pan.
In a large bowl, mix cake mix, melted butter or margarine, 1 teaspoon vanilla, and 2 eggs with an electric hand mixer.
Press the cake mixture in to the pan.
In a separate large bowl, mix together the cream cheese, 2 more eggs, and vanilla with an electric mixer. Slowly add in the confectioner's sugar. Pour over cake layer.
Bake for 40–50 minutes, or until cake is done but center is gooey.