Wash the potato and cut out any bad bits. Dry the potato with a paper towel or a towel. Pierce the potato several times with a fork.
Put the potato on a paper towel. Put it in the microwave and cook on high power for 8 - 10 minutes depending on the size of the potato and how many you cook at once. Turn the potato over and cook for another 8 - 10 minutes until the potato is soft. (It is very easy to over cook in a microwave so be careful.)
While the potato is cooking, prepare your filling (chop, grate slice, dice etc.)
When the potato is soft, take out of the microwave and cut the potato in half, lengthwise.
Scoop out the flesh of the potato using a tsp leaving an edge all the way round. Put the flesh in a large bowl, add margarine and milk and mix until smooth like a paste.
Mix in the filling, reserving some of the grated cheese for later.
Put filling back into the 2 potato shells. Place on a piece of aluminium foil, sprinkle on remainder of cheese and put under the grill until cheese has melted.
Once the cheese has melted take the potato out of the grill. The Stuffed Baked Potato is done.