Melt butter in a medium sauce pan over low heat.

Whisk in flour, constantly whisking until flour mix turns to a paste...about 2 min, not letting it turn brown.

Slowly add milk, while continue to whisk constantly.

Turn heat up to med, continue cooking until sauce thickens. 4 or 5 minutes more.

Stir in salt and pepper.

It can be kept in a jar in fridge up to a week.

Makes 1 1/2 cups