Twice Baked Potatoes

Recipe from Sandy Olsen

4 russet potatoes (7-8 oz each); scrubbed, dried, & rubbed lightly with vegetable oil
4 oz shredded Sharp Cheddar cheese (1 cup)
½ cup sour cream
½ cup buttermilk
2 tbls unsalted butter, room temperature
3 medium scallions, white & green parts, sliced thin (½ cup)
½ tsp salt
Ground black pepper

Adjust oven rack to upper middle position and heat oven to 400 degrees.  Bake potatoes on foil-lined baking sheet until skin is crisp, deep brown, and skewer easily pierces flesh (approx 1 hour).  Setting baking sheet aside, transfer potatoes to wire rack and let sit until cool enough to handle, about 10 minutes.  Using an oven mitt, cut each potato in half so blunt side will rest on work surface.  Scoop flesh into medium bowl leaving 1/8-1/4-inch thickness for shells.  Return shells to baking sheet, bake until dry and slightly crisp, about 10 minutes.  Meanwhile, mash potato flesh with fork until smooth; stir in remaining ingredients until well combined.  Remove shells from oven and increase oven setting to broil.  Using oven mitt, spoon mixture into crisp shells, mounding slightly at center and return to oven.  Broil until spotty brown, approx 8 minutes.  Allow to cool 10 minutes.  Serve warm.  Prep time: 1½ hours.