In a small saucepan, melt the butter over medium heat. Once fully melted, gradually whisk in the flour. Stir constantly until a smooth paste forms. Allow the mixture to bubble gently for one minute to eliminate any raw flour taste, taking care not to let the butter brown.
Incorporate the Milk:
Slowly pour in the milk while whisking continuously to ensure a smooth and lump-free mixture. Increase the heat slightly and bring the sauce to a gentle boil, then reduce the heat to a simmer.
Thicken the Sauce:
Continue whisking the mixture over low heat until it thickens to your desired consistency. This typically takes about 2-3 minutes. Be patient and maintain a consistent stirring motion.
Season the Sauce:
Once the sauce has thickened, add salt and black or white pepper to taste. If desired, incorporate a pinch of ground nutmeg for a subtle layer of flavor. Whisk briefly to combine all ingredients.
Notes
To make this recipe gluten-free, replace the all-purpose flour with a gluten-free 1:1 baking flour. Ensure all additional ingredients, such as butter and milk, are certified gluten-free to avoid cross-contamination.