Flan Cake

I couldn't sleep the whole night after the first time I ate this cake.
It was my freshman year. One of my senior dorm mates was finishing her practicum and she needed a guest to her Practice House Experience's final dinner party. I was so excited. After all it was my first intro to the adult social life.
My culinary knowledge was very provincial. The only dessert I knew then was either a piece of ripe banana or a peanut brittle. Then came this dessert. I knew the leche flan. One of my aunts always prepared some in several llaneras (leche flan molds) during fiestas. But how did the spongy cake get under the flan? Were they cooked separately and just put together before serving? I couldn't imagine the two being baked at the same time in the same pan because I was so sure they would have gotten mixed together somehow. During my time, you had to do your own research before you asked questions.
I had to wait for a whole year before I would be enrolled in a food preparation class. That was how long it would take me to find the answers.