Directions

1. Put potatoes into a large saucepan, and cover with cold water. Bring to a boil; reduce to a simmer, and cook until just tender when pierced with the tip of a knife, 15 to 20 minutes. Drain well. Transfer to a rimmed baking sheet, and let stand until cool enough to handle.
2. Cut off tops and a thin slice from bottoms of 24 potatoes. Using a small melon baller, scoop out flesh from these potatoes, leaving a 1/4-inch-thick shell. Peel remaining 4 potatoes. Press all flesh through a ricer into a medium bowl.
3. Preheat oven to 375 degrees. Heat milk and 1 tablespoon butter in a small saucepan over medium heat until butter melts. Stir into riced potato, a little at a time, until creamy. Stir in crème fraîche, 1 teaspoon salt, and the chives; season with pepper.
4. Transfer to a pastry bag fitted with a 1/2-inch plain round tip (such as Ateco #806). Pipe into shells, mounding about 1/2 inch above top edge.
5. Bake until tops are golden brown and slightly puffed, about 15 minutes. Brush with melted butter, and bake 15 minutes more. Top each potato with about 1/4 teaspoon caviar, and sprinkle with chives.