How to Make It
Preheat the oven to 400°. Prick the potatoes a few times with a fork and bake on a rack in the oven for about 40 minutes, or until tender.
Meanwhile, in a small bowl, blend the crème fraîche with the garlic; season with salt and white pepper and let stand for at least 15 minutes.
Increase the oven temperature to 450°. When the roasted potatoes are cool enough to handle, cut them in half lengthwise and scoop the flesh into a medium bowl, leaving a thin wall around the skins. Reserve 8 of the potato skin halves; set aside the rest for another use or discard. Mash the flesh well with a potato masher, then gently mash in 2 1/2 tablespoons of the butter and the warm cream and season with salt and white pepper.
Rub the remaining 1 tablespoon of butter all over the outsides of the 8 reserved potato skins and season with salt and pepper. Arrange the potato skins, cut sides up, on a baking sheet. Bake in the upper third of the oven for about 3 minutes, or until the skins are lightly crisp. Spoon the filling into the potato skins and continue baking for about 10 minutes, or until heated through and glazed on top.
In a medium saucepan, heat the crème fraîche. Add the shrimp and cook over moderate heat, stirring occasionally, until pink and starting to curl, about 3 minutes. Using a slotted spoon, transfer the shrimp to a plate. Increase the heat to moderately high and simmer the crème fraîche until slightly reduced, about 2 minutes. Return the shrimp to the sauce.
Set 2 baked potato halves on each plate. Spoon the shrimp and crème fraîche sauce over the stuffed potatoes and serve immediately.