Pre-heat the oven to 425 degrees. Rub a large baking dish with oil (or line it with parchment/foil) and briefly set aside.

In a small bowl, whisk together the olive oil, garlic, maple syrup, cinnamon and cayenne until well combined. Set aside.

Scrub the sweet potatoes and pat them dry. If some of your potatoes don’t lie flat on a cutting board, cut a narrow slice from the bottom of the oddly shaped potato for them to rest on. Now it’s time to “hasselback” the potatoes. Place two chopsticks (you can also use two knives or two wooden spoons) on either side of each potato. Carefully cut crosswise slits into the potato at ¼-inch intervals, stopping before you cut all the way through so that the slices stay connected at the base. (The chopsticks/knives are there to stop your knife before you slice all the way through the potato.)

Brush the potatoes all over with half of the oil mixture, including the bottoms, doing your best to get some of the oil into the slits. Arrange the potatoes in the prepared baking dish. Place 4-5 sage leaves in between the slices of each sweet potato, and season the potatoes generously with salt and pepper.

Bake the potatoes for 40 minutes. Remove the potatoes from the oven and brush them with the remaining oil mixture. The potatoes should have started to fan out at this point, so make sure you really get in between the slices with the oil. (If your potatoes haven’t fanned, don’t freak out. You can gently nudge the layers apart with the back of a fork.) Season in between the layers with an extra pinch of salt.

Return the potatoes to the oven and bake for 25-30 minutes until they’re very tender and the edges are crisp. Sprinkle each of the potatoes with Parmesan cheese (again, make sure you get down in the slits, people), and bake for a final 5-7 minutes until the cheese is melted and lightly browned. Serve immediately.