Transfer the liquid to a fat separator and let sit for 5 minutes to allow fat to separate. Return 2/3 to 3/4 cup of the fat to the roasting pan and place over medium-high heat. Discard any remaining fat. Add the flour and whisk to combine. Cook, whisking continuously, until the mixture starts to thicken and become smooth, 2 to 3 minutes. Once this happens, gradually add the liquid back to the pan and whisk until smooth and you have reached your desired consistency, 5 to 6 minutes. Remember, your gravy should be slightly thin in the pan as it will thicken once you serve it. Add the herbs and whisk to combine. Season to taste with salt and pepper.