Place the warm water in a large bowl and slowly add the cornmeal. Season with the salt and knead the dough until it's smooth. If you notice that the dough is still dry, add more warm water little by little until you get a smooth texture.

Divide the dough into 4-5 big pieces. Shape each piece into a big ball and then flatten it with you hands to form a disc that is about ½ inch (1¼ cm) thick. If you get any cracks around the border, you can flatten and seal them with your fingertips.

Melt a little bit of butter in a large pan or griddle over medium high heat and grill the arepas for about 5-7 minutes per side. Remove them from the pan and let them cool for a bit.

4. Cut the arepas in half with a serrated knife making sure not to cut them all the way through. Place 2 slices of ham inside of each arepa with 2-3 tbsp of shredded mozzarella cheese or 2 slices of mozzarella.

Lower the heat to medium, place the arepas back on the pan or griddle and cook until the cheese starts to melt. Serve immediately.