To make the flan mixture, combine all of the ingredients in a blender leaving out ½ cup of cajeta. Mix until completely combined.
Spray a bundt cake pan mold with non-stick spray and use a spoon to drip the ½ cup of cajeta on the bottom of the mold. Line the pan with a thin layer of cajeta.
Pour the flan mixture on top of the layer of cajeta inside the mold.
Cover with aluminum foil until fully sealed.
Place the baking dish in a large pan or pot, making sure the baking dish fits sitting down inside the pan. Pour about 1 inch of very hot water in.
Place the pot on the stove and cook over medium heat for 1 hour, making sure there is still water in the bottom of the pan. If you see that the water is evaporating completely add a bit more hot water.
Let the flan cool completely for at least two hours.
Remove the foil. Turn the pan over on a platter to release the flan. The Cajeta that was at the bottom of the bundt pan should now cover the flan and flow down to the side of the flan on the platter. Now it is ready to serve.
Video
Notes
Leftover Flan. Any leftover flan can be stored in the refrigerator in an airtight container for up to 3 days.
Faster Option. To help speed up the cooling process, place the mold in an ice bath or in the refrigerator. I haven't tried cooling the flan down in the freezer but I see no reason why you can't. Just make sure to check on it frequently as you don't want frozen flan.
Smooth. To ensure that your flan is ultra-smooth and does not have any bubbles, pass the blended mixture through a fine sieve before adding it to the cake mold.
Water Level. Make sure to regularly check the water level of the pan. When you notice that some of the water has evaporated, top it off again with a little more water.