Optional seasonings: Salt & Pepper, Worcestershire sauce
Place the pan drippings from cooking your meat (get every last drop and loosened browned drippings) in a fat separator, or through a mesh strainer. If you don't have 3 cups, add the remainder of beef or chicken broth. If I'm making a roast, I will add beef broth. If I'm making turkey gravy, I will use chicken broth.
First make the roux. Melt 3 Tablespoons of butter over medium heat in a large saucepan. Allow to start to bubble. Whisk in 3 Tablespoons of flour and whisk until it has thickened and formed a paste. Cook for 3-5 minutes or until smooth and creamy. Wait to add any seasonings until after the broth has been added.
Then slowly whisk in the broth from the meat. Alternate whisking and adding liquid until you reach the consistency you like. Bring to a light simmer. Cook until it has thickened, about 3 to 5 minutes. If you'd like a thicker gravy, add less liquid. Add more liquid for a thinner gravy.
Season with salt and pepper (or additional seasonings), to taste. Add a dash or two of Worcestershire if desired. Serve over meat and mashed potatoes.