Melt butter on medium heat in a heavy sauce pan.
Add the flour and whisk for 1 minute.
Add in half the milk while whisking to eliminate lumping, then add the remaining milk.
Bring to a boil, add the bay leaf, salt, pepper, and nutmeg, then reduce to a simmer.
Simmer for 10 minutes, then add dijon mustard and wine and whisk to combine.
Remove from heat and serve hot over vegetables.
Garnish with toasted bread crumbs, as follows
In a nonstick skillet on medium high heat, melt 1 tbsp butter
Add bread crumbs and stir to coat with butter
Stir continually until the crumbs are toasted, 4 to 5 minutes