One Large Potato - Must be fresh. Potatoes keep for a really long time, but their taste goes downhill after a while. Rinse off the dirt, poke it full of holes with a fork, and toss it into a 400-450oF toaster oven for an hour.
An hour later, slice it open with the fork, push in the ends so the potato innards crumble and you end up with a more or less round opening, and add:
Butter - I'm a big fan of "real" food. Margarine is manufactured food. Anything made solely by partially dehydrogenating something is not real food.
Black Pepper - Freshly ground is the best way to go.
Cheddar Cheese - I've found that slices are the most convenient. Shredded spoils too fast, and blocks take too much work. For a baked potato, I just fold a slice into quarters to break it apart, then insert the pieces into the potato and wait until they melt before adding more things.
Sour Cream - Cream is a type of fat. Reduced-fat or non-fat fat is obviously not real food (see butter). Also, if the ingredients include guar gum, carageenan, plastic, or anything other than milk, cream, and enzymes ... it's not worth eating. If you don't like fat, plain yogurt is good too - different in taste, but still good.
Diced Ham - I'm too lazy to mess with bacon.
Fresh Chives - I'm the proud owner of a one-pot herb garden that I started after buying some potted chives on a whim at the grocery store. Lucky for me they turned out to be rather hardy. Chives lose their flavor very quickly after being cut from the plant, so it's good to not harvest until the last minute. I rinse mine under some water, then cut them up with scissors.
Once everything is added, use the fork to mash it all together. Eat.
For slightly more work (in that it requires turning on a stove), I've also enjoyed baked potatoes stuffed with:
Fry them in a pan (adding in the above order) with some olive oil, salt, and black pepper, then pour over the potato. This mixture doesn't really mix well with the first list.