Tarta de queso, best cheesecake ever

I have been to Madrid for a few days and had the opportunity to try different restaurants serving tarta de queso. What can I say…simply the best cheesecake I’ve ever had, much better than any other cheesecake like New York Cheesecake or Japanese Cheesecake. What I really appreciated was the combination of a firm, slightly harder outside and a creamy, melting inside, it was just so, so, so good. In particular, I loved the one from Alex Cordobes’s shop and another I had at a restaurant in the Salamanca district, La Bien Aparecida.

I would like to know if these kinds of cheesecake are typical of Madrid or if they come from somewhere else (for example, I didn’t try the Basque cheesecake, maybe it’s very similar to the ones I had). I’m also very interested to know what kind of cheese is used in these cakes.