Preheat the oven to 350 degrees F. Spray a 1-quart baking dish with cooking spray and set aside.
Drain the canned yams, transfer them to a large mixing bowl, and mash them with a potato masher or the back of a wooden spoon. Add the melted butter, brown sugar, egg, cinnamon, and salt, mixing well. Fold in the crushed pineapple.
Spread the mash evenly in the prepared baking dish. Bake uncovered for 30 minutes. Remove the dish from the oven and top with the marshmallows and chopped pecans.
Turn on the oven broiler and return the dish to the upper middle rack. Broil for 1 to 2 minutes, or until marshmallows are lightly browned.
This nutrition information is based on the exact products I used in this recipe. Brands and sizes of products could alter exact nutrition and should always be calculated independently.