Bring cast iron pan back to stovetop over medium high heat. Add shallots, garlic and cook 1-2 minutes. Add wine, scrape brown bits from the bottom with a wooden spoon, raise temp and bring to a boil. Taste sauce for seasoning, might not need any or possibly only a little pepper. Cook over a simmer for about 10 minutes to reduce by half, add a final pat of butter and stir.