Melt the butter in a medium sized saucepan over low-medium heat. Add scallions and mushrooms and sauté, stirring often, until the vegetables are softened, about 4 to 5 minutes.

Sprinkle flour over vegetable mixture and whisk in to blend. Turn heat up to medium and cook for a minute or two or until flour just begins to color.

Slowly add about 4 cups (960 ml) of stock, whisking all the while, until smooth. Continue to cook, whisking occasionally, until gravy begins to thicken. This will only take a few minutes. Add additional stock if necessary to achieve a nice thick but flowable gravy. Whisk until smooth. Season to taste with salt and pepper taking into consideration that you will need less (especially salt) if you will be adding pan drippings. We do think that a generous amount of pepper improves the gravy greatly.

The gravy is ready to use, or you may whisk in pan drippings at this time, in which case the color will be greatly enriched. You may also cool the gravy at this point (before or after adding pan drippings) and then refrigerate in an airtight container for up to 3 days. Reheat over low heat on the stovetop when needed