Gather all ingredients.

Melt butter in a large saucepan over medium heat. Add flour and whisk until smooth. Cook and stir until roux is a light, golden, sandy color, about 7 minutes.

Increase heat to medium-high and slowly whisk in milk until thickened. Bring to a gentle simmer, then reduce heat to medium-low and continue simmering until flour has softened and no longer tastes gritty, 10 to 20 minutes.

Season with salt and nutmeg.

Serve hot and enjoy!