Preheat and Prep: Preheat your oven to 375°F (190°C). While the oven is heating, peel and slice the yams into ½-inch thick rounds. Place them in a large mixing bowl.

Make the Syrup: In a small saucepan over medium heat, combine the melted butter, brown sugar, cinnamon, nutmeg, salt, and vanilla extract. Stir until the sugar is dissolved and the mixture is well combined, about 2-3 minutes. If using orange juice or rum, add it now for extra flavor.

Assemble the Dish: Arrange half of the yam slices in a single layer in a greased 9x13-inch baking dish. Evenly spread half of the crushed pineapple over the yams. Drizzle with half of the syrup. Repeat the layers with the remaining yams, pineapple, and syrup.

Bake: Cover the baking dish with aluminum foil and bake in the preheated oven for 30 minutes. Remove the foil, sprinkle the coconut flakes evenly over the top, and return to the oven. Bake for an additional 15-20 minutes, or until the yams are tender and the coconut flakes are golden brown.

Serve: Let the dish cool for a few minutes before serving. The syrup will thicken as it cools, making for a luscious, sticky coating on the yams. Garnish with extra coconut flakes or a sprinkle of cinnamon if desired.