In a medium bowl, mix 2 cups of masarepa, 1 teaspoon of salt, 1 cup of crumbled Cotija cheese, 2 tablespoons of softened butter, and about 1 and ¼ cups of warm water until smooth.

Knead the dough gently for 2-3 minutes until it becomes smooth and pliable, then let it rest for 10 minutes.

Divide the dough into eight equal portions, roll each into a ball, and flatten into discs about 5 inches in diameter.

Place about 2 tablespoons of shredded mozzarella cheese in the center of one disc, cover with another disc, and press to seal.

Heat 1-2 tablespoons of oil or butter in a skillet. Cook each side of the arepas for 4-5 minutes until golden brown.

Check for doneness by slicing one open to ensure the mozzarella is melted. Serve warm.