Place the spinach leaves in a very large, deep skillet. Add 2 tablespoons of water.
Cover (ideally with a clear lid so you can peek) and turn the heat to medium-high. When the spinach starts to steam, turn the heat to medium, and keep steaming until the leaves are just wilted, about 5 minutes.
Transfer the cooked spinach to a colander. Press on it with the back of a large serving spoon to extract as much liquid as you can.
Transfer the steamed spinach to a serving plate. Sprinkle with salt, pepper and garlic powder, and drizzle with melted butter and lemon juice. Mix and serve.