Start by melting 4 Tablespoons of butter in a stock pot (medium-sized) on the stove. Heat to high, and once the butter melts, reduce to medium for the remainder of cooking time.
Add the flour and whisk constantly for a few minutes, or until smooth. The flour will turn a slight golden brown color and will smell "cooked".
Add the tomatoes and whisk to combine, about 5 minutes. At this point, you can add chicken stock to thin it out, if you prefer. Season with salt and pepper to taste.
Turn off heat and pour into serving bowl or vessel.
Video
Notes
Be sure to stir the flour and butter constantly until incorporated. This will result in a smooth consistency that is needed for the gravy
If you choose to use fresh tomatoes, you'll need about 4 total. Peel them and crush the tomatoes before adding to stock pot
Use the chicken stock to thin the tomato gravy according to your preference