Insert a skewer or thin knife along the bottom of the potato - this will prevent you from cutting through the whole way. Make slices across the potato the short way about 5mm apart, making sure to cut down to the skewer but not all the way through the potato. The slices should stay connected at the bottom. Remove the skewer and return the potato to the bowl of water, and proceed with the second potato.
Place the potatoes on a microwave safe plate and cook on full power for 3 to 4 minutes. Remove from the microwave and check to see if the potato is tender, return to the microwave for a further minute if still hard in the middle.
Remove from the microwave and add the cheese and butter slices in between and put in the microwave for one more minute. Remove from the microwave and add more cheese, pepper, salt and oregano on the top. Cook for 1 more minute until the cheese is melted. Remove from the microwave and serve.
Substitute with other sliced cheese of your choice.