Preheat saucepan on medium-low heat.
Add butter to hot saucepan.
Shimmy in cornstarch or flour, one tablespoon at a time.
Use a whisk to break down any lumps before adding the next tablespoon.
Stir and cook until lightly golden brown in color to create a roux, approx 4-6 minutes.
Add broth and season with salt, pepper, and garlic.
Add the optional splash of white wine, poultry seasoning, or drippings and simmer on medium heat.
Stir occasionally to ensure the gravy is not sticking to the bottom of the pan. Lower the heat if it is.
Reduce heat to low and simmer once the gravy thickens for a few minutes before serving.