Big thanks to Roberta Broussard and her Chocolate Flan cake. I've adapted her cake in light of the holidays to make a special Christmas treat.
Please feel free to modify it according to your tastes. I wish the cake itself would have that rich eggnog taste, but I'm hesitant to substitute eggnog for the soda. Maybe next time I'll muster the courage.
Preheat Oven to 400 degrees. Spray a bundt cake pan with spray oil (I love Baker's Joy). Pour 1/2 bottle of cajeta or caramel sauce on the bottom of the bundt pan. Set aside.
Prepare cake as called for on box substituting the Cream Soda for the water. Mix well making sure to scrape down the sides. Set aside.
Mix the eggnog, eggs and condensed milk for about 2-3 minutes.
Pour cake mix over the caramel in the bundt pan making sure to evenly distribute the mix. Next pour the flan mixture over the cake. The flan mixture will seep beneath the cake (My kids and I love watching the cake balloon up as the flan mixture goes under).
Place the bundt pan in a larger pan and pour hot water in the larger pan until it comes about 3/4 of the way up the larger pan. This water bath will help the cake and flan (especially the flan) cook evenly.
I cover the bundt pan with aluminum foil to keep the top from burning. Cook for about 45 minutes then remove the foil. Cook for another 15-30 minutes (checking at 5-10 minute intervals) until a toothpick or bamboo skewer inserted in the middle of the cake comes out clean.
Remove the cake from the oven and refrigerate (at least 5-6 hours but preferably overnight). Run a thin knife along the inner and outer edge of the bundt pan to loosen the cake and flan. Cover the top of the bundt pan with the plate or tray you will be serving from (This is much easier than trying to move the cake later). Invert the pan onto the tray and tap the top until the cake is released.
If you did it right and the flan set correctly, you should have a result similar to the picture. Good luck!