Mix the precooked cornmeal, water, salt, and softened butter in a bowl.

Knead until a smooth ball forms.

Cover with a wet towel and let rest for 10 minutes.

Divide the dough into 12 pieces and roll them into balls about 2 inches in diameter.

Press each ball into a disk about 5 inches in diameter in-between sheets of plastic wrap and by using a tortilla press or rolling pin.

Add mozzarella cheese in a mound to the center of half of the disks.

Place the remaining disks on top of the cheese.

Seal the edges by pressing down and inwards. You don't want thin edges, so keep the diameter at 5 inches.

Heat a griddle or large skillet to medium-high heat.

Coat the cooking surface with some vegetable oil.

Cook the arepas on the hot skillet for 3-4 minutes on each side until they are golden brown. You can do them in batches if they won't all fit.

Serve with more butter on top if desired.