Mix the masarepa with the salt (and pepper if using) in a medium heatproof bowl. Add the hot water and the melted butter and mix well. Cover with plastic wrap and let rest for 10 minutes. Add a little more water if needed, if mixture seems dry and crumbly. You should be able to form pieces of dough into balls easily, without many cracks in the dough.

Reserve 2 tablespoons of dough. Divide the remaining dough into 4 pieces, and roll each piece into a smooth ball. Dampen your hands with water to help prevent cracks in the dough when rolling it.

Place one ball between 2 small zip-close bags, or 2 pieces of plastic wrap. Flatten the ball with the bottom of a heavy pan or skillet until it is about 3 to 4 inches in diameter and about 1/3-inch thick. You can neaten the edges of the circle with dampened fingers.

Heat about an inch of vegetable oil in a heavy skillet over medium heat, just hot enough so that a piece of dough sizzles gently.

Fry the arepas for a couple of minutes on each side, until golden.

Remove from heat and place arepas onto a plate lined with paper towels.

When the arepas are cool enough to handle, slice into the side of the arepa with a thin sharp knife in the same way you would split open an English muffin. Hollow out a space in the arepa without slicing all the way through.

Crack an egg into a small ramekin. Sprinkle the egg with salt and pepper lightly if desired. Pour the egg into the hollowed out arepa. Seal the opening with some of the reserved dough.

Return the arepa to the hot oil and fry for 2 to 4 minutes more. Cook the arepa less if you like a runny egg and more if you prefer the egg to be more well done. Repeat with remaining arepas.

Remove from heat, season with salt and pepper to taste, and serve warm.