In a medium sized saucepan, sauté the shallots in 1 tablespoon of the butter until translucent.
Add the wine, thyme, bay leaf and peppercorns and reduce to about ½ cup.
Add the demi glace and again reduce to ½ cup.
Strain the sauce into a small saucepan. (Optional)
Over low heat, slowly add the remaining butter 1 tablespoon at a time using a whisk to incorporate.
Reduce until the sauce is thick enough to coat the back of a spoon.
Taste and adjust seasoning with salt and pepper.