Basic rule of thumb: To thicken 1 cup of stock use 1 tablespoon butter and 1 tablespoon flour.
Make a darker gravy with unbrowned flour by making a dark roux. A roux is a thickener made from equal amounts of fat and flour. Heat the fat, add the flour, and cook over medium heat, stirring constantly until the roux becomes a deep brown. When making gravy with the roux, it will not thicken as well, so you will need more of it.
If all the above tips fail in getting your gravy to brown to a rich color or you just want a quick and easy solution, add 1/8 teaspoon instant coffee granules and stir to blend or you can use kitchen bouquet which is a browning mixture found in local supper markets.
Thin gravy can be easily thickened by adding a mixture of either flour and water or cornstarch and water, which has been mixed to a smooth paste. Add gradually, stirring constantly, while bringing to a boil.
