How to Make It
In a food processor, pulse the corn until a thick, coarse puree forms. Add the masa, egg yolks, salt, sugar, black pepper and cayenne and pulse until well combined. Scrape the cachapa batter into a bowl.
In a large nonstick skillet, heat 1 tablespoon of the oil. Scoop 3 slightly heaping ½-cup mounds of batter into the skillet and spread them into 4- to 5-inch rounds. Cover and cook over moderate heat until the tops are set and the edges are beginning to brown, about 6 minutes. Carefully flip the cachapas, cover and cook until browned on both sides and a skewer inserted in the middle of each one comes out clean, about 6 minutes. (Reduce the heat to moderately low if the cachapas brown too quickly.)
Sprinkle each cachapa with 2 tablespoons of the mozzarella and 1 tablespoon of the queso fresco, cover and cook until the cheese is melted, about 3 minutes. Top each cachapa with a few jalapeño slices and 1 tablespoon of cilantro, then carefully fold them in half and transfer to a platter. Keep warm. Wipe out the skillet and repeat to make 3 more cachapas.
Sprinkle the cachapas with the remaining 6 tablespoons of queso fresco and 2 tablespoons of cilantro and serve with lime wedges.
Masa harina is a soft flour made from finely ground dried corn kernels. It can be found in the ethnic food aisle of most grocery stores.