Set the oven to 375°F (190°C) and line a baking sheet with parchment paper. Spread out the frozen crab legs in a single layer, making sure they are not stacked to promote even cooking. Bake on the middle rack for 15 to 20 minutes. Once the timer goes off, carefully touch the shells to ensure they are sufficiently heated. If they are not hot, continue baking in 5-minute intervals until warmed through. Serve hot with ghee or melted butter.