Heat oven to 425° and lightly oil a baking dish.
Cut vertical slits in the potatoes, stopping about ½” from the bottom so that everything stays intact. The slits should be about ¼” apart of each other. To make things a little easier, you can place the potato between the handles of two wooden spoons and stop cutting once you get to the spoon handles.
Place the potatoes in the baking dish, and brush with half the oil. Sprinkle on about half of salt. Try to get some of the oil and salt in between the slices.
Cook the potatoes for 30 minutes. Remove from the oven. Brush on the rest of the olive oil, and sprinkle each potato with the minced garlic, nutritional yeast, rosemary, black pepper, red pepper flakes, if using, and the rest of the salt. The potatoes slices should have started to peel away from each other, so try to get into the spaces with the oil and seasonings. You have to pry them apart gently to get into the spaces.
Bake for another 30 minutes, until the potatoes have browned nicely, and the edges are crispy.