Collect and measure all the required ingredients according to the ingredient list.
Melt butter in a saucepan over medium heat.
Add flour and whisk continuously for 1–2 minutes to form a roux.
Gradually pour milk into the roux while whisking to prevent lumps.
Heat the milk for around 5 to 7 minutes.
Continue stirring while heating until the sauce thickens and becomes smooth.
Season with salt, black pepper, chili flakes, and a pinch of nutmeg (optional).
Again, mix nicely and simmer for 1 to 2 minutes.
Remove from heat and use immediately, or store in airtight container in the refrigerator for later.
