In a large skillet, melt 3 tbsp. butter over medium-high heat. Add the shallots and cook, stirring often, until softened, about 5 minutes. Add half of the mushrooms to the pan and cook, stirring occasionally, until golden, about 5 minutes. Transfer to a plate. Repeat with the remaining 3 tbsp. butter and mushrooms. Return the first batch of mushrooms to the pan.
Stir in the wine and cook, stirring occasionally, until almost evaporated. Sprinkle in the flour and cook, stirring, for 1 minute. Stir in the turkey stock and bring to a boil, stirring constantly; lower the heat and simmer until thickened, 3 to 5 minutes.
Season the gravy with salt and pepper. Stir in the parsley. Keep warm, or reheat when ready to serve.