Place the plantains in a medium pot and cover with water. Cook over medium heat for about 8 - 10 minutes.
Remove the plantains from the water and peel. Mash with a potato masher or a fork.
Form 15 balls of about 1 ½ to 2 tablespoons of plantain mash. Flatten them with your hands and place 1 piece of guava paste and 1 piece of cheese in the center.
Form the ball again and place in a heavy pot with hot oil, over medium high heat. Fry for about 4 minutes turning over once, until golden brown.
Using a slotted spoon, transfer to a plate lined with paper towels to absorb the oil. Serve hot and sprinkle with sugar if you like.