Use only 9-inch, light-colored pans; 8-inch pans are too small to hold the caramel and flan mixtures, and dark pans may scorch the flan.
You might like to use a 13x9-inch pan for the shallow pan of water. The pan of water is used to provide moisture and ensure even baking of the cake.
Don't be surprised if some of the caramel soaks into the flan and cake during cooling. This adds to the richness of the cake.