Beef gravy made with either pan drippings or bouillon is almost a necessity with mashed potatoes or the meat itself. Unless you are planning to serve the gravy "au jus" style, you will want to thicken the sauce before serving. You can thicken beef gravy by different methods and each depends on what ingredients you have on hand in the pantry. You can use these methods to make a thick, rich gravy with water, broth or milk.
Thicken with Flour
Measure 1/4 c. of beef pan dripping and pour it into a saucepan.
Mix 1/4 c. of flour with 1/4 c. of water in a small jar. Place the lid on the jar and shake vigorously to mix thoroughly.
Heat the pan drippings in the saucepan over medium high heat.
Pour in the flour mixture and stir to incorporate it into the drippings.
Continue to stir until thick. Add in up to 1 c. of water, broth or milk and keep stirring until the mixture thickens to the desired consistency.
Thicken with Cornstarch
Mix 2 tbsp. cornstarch with 1/4 c. of water in a measuring cup or small bowl. Use a whisk to remove any lumps that may form.
Pour the bouillon into a saucepan and add the cornstarch mixture.
Bring the liquid to a boil, whisking constantly.
Continue to whisk the liquid until it becomes thick enough to serve as gravy.