To avoid the tortilla to be burned but at the same time avoid the tortilla for not being well cooked on the inside put kitchen at mid level, but also inclinate the pan a little bit, so the liquid gets in by the sides of the pan.

About the green paper on top, that is how the usually prepare it in bars when you ask for a a) "pulga de tortilla" or a b) "bocadillo de tortilla"

a) Small french stick bread with tortilla
b) French stick bread with tortilla

Adios!