Preheat your oven to 400°F (200°C). Toss the chopped sweet potatoes with a tablespoon of olive oil, salt, and pepper, then spread them evenly in your baking dish.
Roast the sweet potatoes in the oven for about 25-30 minutes, or until they start to soften and turn golden around the edges.
Meanwhile, remove the sausage from its casing and crumble it into a skillet over medium heat. Cook, stirring frequently, until browned and cooked through, about 8-10 minutes.
Slice the apples into thin wedges and chop the sage finely. Once the sausage is cooked, add the apples and sage to the skillet and cook for another 3-4 minutes, just until fragrant and slightly tender.
Remove the sweet potatoes from the oven once they are lightly caramelized, then gently fold them into the sausage mixture, mixing everything well.
Transfer the entire mixture back into the baking dish if necessary, then sprinkle breadcrumb evenly over the top. Drizzle with melted butter for a crispy, golden finish.
Bake the casserole for an additional 15 minutes, or until the top is bubbly and golden brown.
Remove from oven and let rest for a few minutes. Serve hot, garnished with extra sage if desired. Enjoy the rich aromas and hearty textures.
