- 5 minutes
Melt butter in a small saucepan.
Add in shallots and cook over medium to medium-high heat for 2 minutes, then add in flour and stir well. It should look like wet sand--this is the roux and will thicken the sauce.
Pour in wine, stir well and cook for 1 minute, then pour in milk and stir regularly--or better yet, use a whisk, (scrapping the sides and bottom) until it simmers gently, is smooth and thick.
Once the sauce thickens, remove from heat and add in parmesan cheese. Stir well to combine. Taste and adjust seasonings with sea salt.