1. Preheat oven to 450°.
2. Combine potatoes and oil; toss to coat. Arrange potatoes, cut sides down, in a single layer on a parchment paper–lined baking sheet. Bake at 450° for 20 minutes. Turn potatoes; bake 10 minutes. Remove and cool 20 minutes.
3. Preheat broiler to high.
4. Using a paring knife, carefully cut a circle in the cut side of potatoes. Using a melon baller or small spoon, remove pulp from potato, leaving a thin shell. Combine pulp, sour cream, 1 tablespoon chives, and next 5 ingredients (through pepper). Evenly fill potato shells with filling; sprinkle with cheese and remaining 1 tablespoon chives.
5. Broil potatoes for 2 minutes or until cheese is lightly browned.