Homemade Gravy - Ina Garten recipe

1/4 pound (1 stick) unsalted butter
1 1/2 cups chopped yellow onion (2 onions)
1/4 cup flour1 teaspoon kosher salt
1/2 teaspoon freshly ground black pepper
Defatted turkey drippings plus chicken stock to make 2 cups, heated
1 tablespoon Cognac or brandy
1 tablespoon white wine, optional
1 tablespoon heavy cream, optional

In a large (10 to 12-inch) saute pan, cook the butter and onions over medium-low heat for 12 to 15 minutes, until the onions are lightly browned. Don't rush this step; it makes all the difference when the onions are well-cooked. Sprinkle the flour into the pan, whisk in, then add the salt and pepper. Cook for 2 to 3 minutes. Add the hot chicken stock mixture and Cognac, and cook uncovered for 4 to 5 minutes until thickened. Add the wine and cream, if desired. Season, to taste, and serve.