Here is an easy Sweet Potato Casserole with Pecans and Marshmallows recipe. It’s the great Thanksgiving side dish or Christmas dinner recipe. This post breaks down the steps on how to make a sweet potato casserole. If you are looking for a tasty, traditional Thanksgiving recipe or Christmas side dish this casserole is for you. It’s a combination of creamy roasted sweet potatoes, a crunchy brown sugar pecan streusel with a gooey marshmallow topping.