These have many variations. The best and freshest potatoes make a dish with the best flavor.Old potatoes or green ones should be avoided. Nice fresh Idaho baking potatoes are best. You can bake them in a 400 degree oven for an hour or so, or microwave them for 10-15 minutes (for 4) for the first round of cooking. The taste is sometimes better if they are baked - rub them with a little oil first and bake directly on the oven rack to get a nice crispness to the skins. Microwaving them seems to make them less dry.
When they are cooked so that a fork goes in easily, cut them in half long-ways and scoup out the middles, leaving just enough potato on the skin so that it retains a boat-like shape and does not fall apart. If the skins fall apart - do no despair - the dish will taste fine - just not look as good. For 4 potatoes: Put the potato middles in a bowl with some mayonnaise (1/4 c or so) some low fat cottage cheese (1/2 a 16oz container) and mustard (1-2 tsp - I like honey or dijon) and mash the potatoes. Then add some dill (1-2 tsp or more) salt & pepper to taste, and 1/2 - 1 cup of grated cheddar cheese and mix well. Lay the shells out in a flat casserole dish (microwaveable, if you are going to nuke them)- or on a baking sheet - or even on the pizza stone. Mound the potato mixture back into the shells and sprinkle the tops with paprika. Bake them 30 minutes at 350 F or so - or microwave them for 15 minutes on 70 + 5 minutes on 80% power.
Our favorite accompaniment is steamed broccoli -Cooked until it is just bright green and still crisp, it makes a perfect paring with the potatoes in color and texture. Freshly steamed green beans also work. You could chop and mix the broccoli with the potato mixture before baking - or add in some fresh steamed spinach - but we like this dish best with the potatoes and cheese alone - smooth and creamy - and the crisp green broccoli on the side.
You can find a picture here: http://365vegetariandays.blogspot.com/2011/02/day-89-stuffed-potatoes.html