Preheat your oven to 400°F (200°C). Toss the peeled and sliced root vegetables with olive oil, salt, pepper, and a splash of apple cider in a mixing bowl until evenly coated.
Spread the seasoned vegetables in an even layer in a baking dish. Roast in the oven until tender and caramelized around the edges, about 30-35 minutes. Give the dish a gentle shake halfway through for even roasting.
While the vegetables are roasting, heat a small amount of olive oil in a sauté pan over medium heat. Add the sage leaves and cook until crispy and fragrant, about 1-2 minutes. Remove and set aside on paper towels.
When the vegetables are done roasting, transfer them to a serving dish or keep in the baking dish. Sprinkle the shredded cheese evenly over the hot vegetables so it begins to melt.
Scatter the crispy sage leaves on top of the casserole for a burst of herbaceous crunch. Drizzle a little additional apple cider if desired for extra flavor and moisture.
Serve the casserole warm, allowing the cheese to be gooey and the sage to add a crispy texture. Enjoy the comforting blend of savory roasted vegetables with a fall-inspired twist.
