1Prepare one tomato and 2 slices bacon for each person to be served
Cut firm green tomatoes horizontally into 1/8" thick slices (each tomato will yield about 4 slices) and set aside
2Fry bacon in a cast iron or other heavy skillet until done but not crisp, set aside
Leave pan with grease intact on medium high heat
3Place Bisquick, salt and pepper in ziplock bag and shake to mix.
Transfer tomato slices in batches to ziplock bag, vigorously shake to fully coat each tomato slice.
Note: you will probably have to prepare more than one batch unless your skillet is awfully large
4Transfer coated tomato slices to bacon grease and cook until crispy brown on both sides.
Remove to cooling rack.
Continue cooking batches until all tomatoes are cooked.
Arrange tomatoes on serving platter.
5Using same skillet and same bacon grease, add 1 tablespoon of all purpose flour per 1 tablespoon of grease (you can eyeball this step) and stir together to make a dark roux; season with salt and pepper.
Add 1 small can evaporated milk diluted with 1 to 2 cups water to roux, cook stirring constantly until mixture thickens.
Pour gravy over tomatoes and garnish with bacon slices.