With a fork, pierce each potato in several places. Microwave until tender when pierced with a fork, about 12 minutes, turning halfway through.
When the potatoes are cool enough to handle, cut in half lengthwise. Scoop out the flesh, leaving a ¼-inch border and transfer the flesh to a medium-sized bowl.
Add the cream and skim milk to the bowl with the potato and mash with a potato masher.
Stir the cumin, salt, pepper, black beans, green onions and ½ cup cheddar cheese into the potato mixture.
Place the potato skins on a baking sheet and divide the potato mixture evenly between the skins. Divide the remaining ¼ cup cheddar cheese between the stuffed potatoes.
Bake the potatoes until the cheese is melted and the skins are slightly crisp, about 15 minutes.