Heat milk in a pot over medium heat. Season with salt and pepper. Add the bay leaf and freshly grated nutmeg to taste. Add sugar, whisk thoroughly, and let simmer for approx. 5 – 7 min. Discard bay leaf, remove milk from heat, and pour into a large measuring cup. Set aside.
Add butter to another pot and melt over medium heat. Be careful not to burn the butter. Sift flour into the melted butter. Stir continuously until a roux forms. Add the hot milk to the roux. Whisk vigorously until the consistency becomes smooth. Add lemon juice and season with salt and pepper. Whisk thoroughly. Enjoy in creamy mac and cheese or lasagna, or use it as a rich base for more complex white sauces!