A super-easy side dish that has always been a hit with my family for both Thanksgiving and Christmas.
Preheat the oven to 350 degrees F (175 degrees C). Lightly grease a 9x13-inch baking dish.
Place whole sweet potatoes in a large pot and cover with water; boil until soft. Transfer to a cutting board; when cool enough to handle, remove skins. Cut into bite-sized pieces; transfer to prepared baking dish.
Add crushed pineapple, brown sugar, and butter to baking dish; stir to combine.
Bake in the preheated oven until casserole mushy with no excess water in dish, about 45 minutes.