Whisk 1 cup water, onion soup mix, Worcestershire sauce, garlic, and black pepper together in a bowl. Strain mixture, reserving solids and broth. Pour 1/2 cup broth and the solids into a large bowl; mix turkey, bread crumbs, and egg into broth-solids mixture until thoroughly combined. Scoop 8 portions using 1/2 cup measure and form each into an oval patty; arrange on a baking sheet.
Bake in the preheated oven until no longer pink in the center and the juices run clear, about 20 minutes. An instant-read thermometer inserted into the center should read at least 165 degrees F (74 degrees C).
Whisk remaining broth, mushroom soup, 1 can water, and gravy mix together in a saucepan until smooth; bring to a boil, stirring constantly. Remove from heat.
Flip patties and pour gravy over each. Continue to cook until gravy has slightly thickened, about 10 more minutes.
