Combine the cornmeal, warm water, cheese, butter and salt, mixing thoroughly. Let mixture stand for five minutes.
Knead with your hands for about 3 minutes moistening your hands with water as you work.
Form 12 small balls with the dough. Place each ball between your palms, pressing to form a thick patty.
Heat oil in a large nonstick skillet over medium heat, then fry arepas in 2 batches, turning over once, until golden, about 3 minutes per side. Drain on paper towels.
Serve with guacamole, hogao, chimichurri or ají.