How to Make It
Preheat oven to 425°F. Slice each potato crosswise at 1/8-inch intervals, cutting to within 1/4 inch of the bottom of the potato. (Do not cut all the way through potatoes.) Arrange potatoes, cut side up, on a greased baking sheet.
Combine melted butter, rosemary, and 1 teaspoon of the salt in small bowl. Spoon 1/3 cup of the melted butter mixture evenly over potatoes.
Bake in preheated oven on middle oven rack until tender, 45 to 50 minutes. Spoon remaining butter mixture evenly over potatoes. Sprinkle with blue cheese and remaining 1/2 teaspoon salt. Bake until cheese is slightly melted and potatoes are golden, about 5 minutes.
Sprinkle with bacon and chives, and serve immediately.