Place potatoes into a very large pot and cover with salted water; bring to a boil. Reduce heat to medium-low and simmer until tender, about 40 minutes. Drain.
Preheat the oven to 400 degrees F (200 degrees C).
Arrange potatoes close together in a 9x13-inch baking dish. Use a fork to press about 1 inch deep in the center of each potato until inner flesh is exposed.
Whisk 1/2 cup olive oil, garlic, and salt together in a small bowl to blend. Drizzle over potatoes.
Bake in the preheated oven, basting occasionally with the oil mixture, until potatoes are crisp and brown on top, about 1 hour 10 minutes. Add additional oil if potatoes seem dry.