I adapted this from a recipe I found on Pinterest, and I must say, my version tastes much closer to the real deal! Very simple and SO rich and delicious! I prefer coconut oil, but vegetable oil works fine too.
Combine cake mix, eggs, sour cream, 1 t of the vanilla, butter flavoring, oil, and 1 cup of the milk with a mixer for 2 minutes.
Pour batter into two greased and floured 9 inch round cake pans.
Bake 40-45 minutes. (This is a very dense cake!).
Cool in pans for 10 minutes, then turn out onto a rack to finish cooling.
Combine the white chocolate and French vanilla pudding mixes with 3 cups of the milk and the remaining t of vanilla. Beat on high speed until it starts to thicken, about 2 minutes.
Beat the chocolate pudding mix, remaining 2 cups of the milk and the powdered sugar on high speed for 2 minutes. Allow pudding mixture to thicken slightly.
Place first layer of cake on cake plate, and cover top with filling. It will be thick and you will probably have some left over. Top with second layer of cake. "Frost" the top only with the chocolate pudding mixture. Cover and refrigerate at least 4 hours before serving.