Wipe out pot and return to stovetop. Melt butter over medium heat until foaming subsides, then add flour and mix into a paste. Continue cooking until raw flour smell is gone, about 5 minutes. Whisking constantly, add mushroom-infused milk in a thin, steady stream, or in increments of a couple of tablespoons at a time, whisking thoroughly and getting into all corners of the pot to maintain a homogeneous texture. Sauce will initially become very thick, then get very thin once all milk is added.
Published at Mon, 13 Nov 2017 10:20:00 +0000