Arrange a rack in center of oven; preheat to 425°. Scrub and dry potatoes. Cut off about 1/4" from one long side of each potato. (This will help keep the potatoes stable on the cutting board.) On cutting board, arrange a potato cut side down in between 2 chopsticks. Make 1/4" slices, being sure not to cut all the way through, using the chopsticks as a safeguard. Turn potato 90° and make perpendicular slices to the previous ones. Repeat with remaining potatoes.
Arrange potatoes on a parchment-lined baking sheet. Lightly brush potatoes with oil; season with salt.
Bake potatoes until inside is tender and outside is crisp, 40 to 50 minutes.
Turn broiler on High. Sprinkle potatoes with cheddar.
Broil, watching closely, until cheese is melted, 30 to 60 seconds.
Divide potatoes among plates. Top with sour cream, chives, and bacon.