Step 1

Arrange 2 racks to divide the oven into thirds and heat the oven to 400°F.

Step 2

Scrub and dry 4 pounds medium russet potatoes. Place on a rimmed baking sheet. Pierce each potato with the tip of a paring knife about 7 times across the surface of the potato. Drizzle the potatoes with 2 tablespoons olive oil and use your hands to rub the olive oil over each one.

Step 3

Place on the lower rack and bake until the potatoes can easily be pierced with a skewer, 45 to 50 minutes. Meanwhile, line a second rimmed baking sheet with aluminum foil. Arrange 12 ounces thick-cut bacon in a single layer on the baking sheet. Bake on the upper rack until browned and crisp, 16 to 18 minutes.

Step 4

When the bacon is ready, transfer to a paper towel-lined plate to drain. Once cool enough to handle, coarsely chop or crumble with your hands.

Step 5

When the potatoes are ready, transfer to a wire rack and let cool until warm to the touch, 30 to 45 minutes. Meanwhile, prepare the remaining ingredients and dressing.

Step 6

Grate 6 ounces sharp cheddar cheese on the large holes of a box grater (about 1 1/2 cups). Finely chop 3 medium scallions (about 1/2 cup). Place both in a large bowl. Add 1 cup mayonnaise and 1 cup sour cream in a large bowl. Add the bacon, cheese, scallions, 1 teaspoon kosher salt, and 1/2 teaspoon black pepper. Stir to combine.

Step 7

When the potatoes are ready, gently peel away and discard the skins. Cut the potatoes into 1-inch pieces. Add to the dressing and gently fold to coat. Cover and refrigerate for at least 3 hours or up to overnight before serving. Taste and season with more kosher salt and black pepper as needed before serving.