Preheat oven to 400. While oven is preheating, put 9 x 13 inch baking dish into oven to melt 1/2 cube of butter. Meanwhile beat together milk, eggs, flour, and salt. When butter is melted, pour the batter into the baking dish. Bake for about 20 minutes. Batter will crawl up the edges of the pan and form peaks. Serve with warm syrup, jam, or powdered sugar.