Creating Sweet Potato & Cranberry Gratin is straightforward if you follow these simple steps:

1. Preheat the Oven: Set your oven to 375°F (190°C).
2. Prepare the Baking Dish: Grease a 9×13-inch baking dish with unsalted butter.
3. Layer Sweet Potatoes: Arrange half of the sliced sweet potatoes in an even layer at the bottom of the prepared dish.
4. Add Cranberries: Sprinkle half of the cranberries over the layer of sweet potatoes.
5. Season: In a small bowl, mix together brown sugar, cinnamon, salt, and pepper. Sprinkle half of this mixture over the cranberries.
6. Repeat Layers: Layer the remaining sweet potatoes on top, followed by the rest of the cranberries and the remaining seasoning mixture.
7. Add Cream: Pour the heavy cream evenly over the entire dish, ensuring it seeps into all layers.
8. Cheese Topping: Sprinkle the shredded cheddar and grated Parmesan cheese evenly across the top.
9. Bake: Cover the dish with aluminum foil and bake in the preheated oven for 30 minutes. Then, remove the foil and bake for an additional 15-20 minutes until the cheese is golden and bubbly.
10. Cool Slightly: Remove from the oven and allow to cool for 5-10 minutes before serving.
11. Optional Topping: For added texture and flavor, sprinkle chopped pecans on top before serving.

These steps will guide you in creating this incredible gratin effortlessly.