Arrange rack in the middle of the oven and preheat to 400ºF.
Rub potatoes all over with olive oil and season with salt and pepper.
Slice a small cross shape into each potato about ¼-inch deep and bake directly on the oven rack for 45 minutes to 1 hour. (For a crispy exterior skin, potatoes can bake up to an extra hour.)
While potatoes bake, arrange favorite toppings into small bowls.
Remove potatoes from the oven and carefully cut deeper into the initial slices. Return potatoes to oven for 10 more minutes.
Remove potatoes from oven, carefully slice lengthwise and insert 1 Tablespoon of butter for each potato. Then push potatoes open further and top with favorite toppings.