The Best Twice-Baked Potatoes...Ever

Why I Love This Recipe
I got this recipe from The Best Recipe book from Cook's Illustrated and haven't really changed it that much (why mess with perfection?). Ocassionally, I'll also top these babies with chopped bacon bits (real ones - not the bottled stuff). People always ask for this recipe when I serve these at a dinner party. Buon Appetite!
When I want to be a little more fancy or formal, I use a pastry bag to fill the shells with the mixture.
Ingredients You'll Need
4 medium russet potatoes, scrubbed, dried, and rubbed gently with vegetable oil
4 ounces sharp cheddar cheese, shredded (about 1 cup)
1½ cup sour cream
1½ cup buttermilk
2 tablespoons unsalted butter, room temperature
½ teaspoon salt
Ground black pepper
Directions
Adjust oven rack to upper-middle position and heat oven to 400 degrees. Bake potatoes on foil-lined baking sheet until skin is crisp and deep brown and skewer easily pierces flesh, about 1hour. Set baking sheet aside, transfer potatoes to wire rack and let cool slightly, about 10 minutes.
Using an oven mitt or folded kitchen towel to handle hot potatoes, cut each potatoes in half so that long, blunt sides rest on work surface. Using a small spoon, scoop flesh from each half into medium bowl, leaving 1/8 to 1/4 –inch thickness of flesh in each shell. Arrange shells on lined sheet and return to oven until dry and slightly crisped, about 10 minutes. Meanwhile, mash potato flesh with fork until smooth. Stir in remaining ingredients, including ground black pepper to taste, until well combined.
Remove shells from oven and increase oven setting to broil. Holding shells steady on pan with oven mitt or towel-protected hand, spoon mixture into crisped shells, mounding slightly at the center, and return to oven. Broil until spotty brown and crisp on top, 10 to 15 minutes. Allow to cool. Serve warm