1. Preheat your oven to 375°F (190°C). Line a baking sheet with parchment paper and toss the sweet potato slices with 1 tablespoon of olive oil, a pinch of salt, and pepper. Spread them in a single layer and roast for about 20 minutes, flipping halfway through, until tender and slightly caramelized.
2. While the sweet potatoes roast, bring a large pot of salted water to a boil and cook the pasta according to package instructions until al dente. Drain and set aside.
3. In a large skillet, heat the remaining tablespoon of olive oil over medium heat. Add the minced garlic and sauté for 1 minute until fragrant. Add the kale and cook, stirring occasionally, until wilted and tender—about 5 minutes. Season lightly with salt and pepper.
4. To make the Alfredo sauce, melt the butter in a medium saucepan over medium heat. Whisk in the flour and cook for 1-2 minutes to form a roux. Slowly pour in the milk, whisking constantly to avoid lumps. Continue whisking until the sauce thickens, about 5 minutes. Remove from heat and stir in 3/4 cup of the Parmesan, nutmeg, and salt and pepper to taste.
5. In a large mixing bowl, combine the cooked pasta, roasted sweet potatoes, sautéed kale, and Alfredo sauce. Gently fold everything together to coat evenly.
6. Transfer the mixture to a greased 9×13-inch baking dish. Sprinkle the remaining Parmesan and mozzarella cheese (if using) over the top.
7. Bake uncovered for 20-25 minutes until bubbly and golden on top. If you like a crispier crust, you can broil for the last 2-3 minutes—just watch carefully so it doesn’t burn.
8. Let the bake cool for about 5 minutes before serving. This helps the sauce set slightly and makes it easier to portion out.

One little trick I’ve learned over the years is to roast the sweet potatoes first—it brings out their sweetness and adds a lovely caramelized flavor that really elevates the dish. Also, don’t rush wilting the kale; cooking it gently helps keep its texture and prevents it from turning mushy. This balance is what makes the bake so satisfying.