In a medium bowl, combine 2 cups of masarepa, 1 teaspoon of sea salt, and 1 cup of warm water. Mix in ½ cup of crumbled Cotija cheese and 2 tablespoons of softened butter until a smooth dough forms.

Check the dough's texture. If it feels dry, gradually add warm water until it becomes pliable and easy to handle.

Divide the dough into 8 pieces and roll each into a ball. Flatten each into a circle about 5 inches in diameter.

Place about 2 tablespoons of shredded mozzarella cheese in the center of one dough circle, then cover it with another circle and seal the edges.

In a skillet, heat 2 tablespoons of oil or butter over medium-low heat.

Carefully place the stuffed arepas in the skillet, cooking for 4-5 minutes on one side until golden brown, then flip and repeat.

Remove from the skillet and let cool slightly before serving. Enjoy warm with avocado, salsa, or sour cream.