My husband is from south Louisiana, Cut Off to be exact and I'm from deep east Texas. Over the years I've tried to learn all his favorite foods to make him feel at home here in Texas. A Bouillie custard is a Cajun staple but, rather than just in a pie (which is typical) his cousin told me about this cake. Basically you make the cake super moist by adding a bit of custard to the batter, then top it with the left overs. I tweaked the recipe a little. (You can also take the custard and add Nilla wafers as it cools. Yummo!!) Everyone in his family loves this recipe, hope you love it too.
Heat Oven to 350 and grease 9x13 pan. You will need another bowl for left over custard.
In a large pot on medium low heat melt butter, add your milk and water. As that is melting, mix butter cake batter as directed on box and pour into cake pan.
Mix sugar, eggs and cornstarch and set to the side. When butter is completely melted add your egg mixture and whisk until pudding like consistency, making sure to stir bottom of pot. DO NOT BOIL, the custard will burn very easily. Turn off heat stir in vanilla. Remove from heat.
Ladle booyee over cake batter evenly to cover do not overfill cake pan. You will have a good bit left over. Bake cake as directed.(I like my cake a little gooey so I do not bake quite as long as directed. Taking it out 2 or 3 minutes before done)
After cake is removed from oven and cooled for about 20 Minutes cut into squares, place on plate then ladle one booyea-custard over baked cake.
This cake is a little labor intensive but well worth it. Refrigerate leftovers, if you have any.