Heat the oven to 425°F.
Cut slits in the potatoes, leaving the bottom intact.
Mix olive oil with garlic salt, paprika and red pepper flakes.
Arrange the potatoes in a baking dish, brush them all over with olive oil mix, including the bottoms.
Bake the potatoes for 30 minutes. At this point, the layers will start separating.
Remove the pan from the oven and brush the potatoes again with the rest of the olive oil. Make sure oil drips down into the space between the slices.
Bake for another 30 to 40 minutes, until the potatoes are crispy on the edges.
Stuff cheese into the slits and sprinkle over the top 5 to 10 minutes before the end of cooking.