Scrub the potatoes under cool running water. Place them in a large saucepan and add enough water to cover. Bring the water to a boil, then reduce the heat, cover the pan, and simmer for 15 to 20 minutes, or until the potatoes are tender. Drain them well.

Once the potatoes are cool enough to handle, cut the top off each one. Use a small spoon to scoop out the pulp, leaving a thin layer of potato inside the skin so each shell holds its shape.

Place the scooped potato pulp and the cut-off tops in a large bowl. Mash them with the butter. Stir in the remaining Parmesan and bacon, then mix in the sour cream, beaten egg, salt, and pepper.

Spoon the potato mixture back into the shells, dividing it as evenly as you can. Sprinkle the reserved Parmesan and bacon over the tops, then add a light dusting of paprika.

Arrange the stuffed potatoes in an ungreased 15-by-10-by-1-inch baking pan.

Bake at 375°F for 12 to 18 minutes. Check the center of the filling with a food thermometer; it should reach 160°F. Serve warm.