Pat turkey breasts dry with paper towels. If breasts are uneven thickness, butterfly or slice horizontally to create even pieces about 1/2 inch thick so they cook evenly and will be easy to pound into cutlets if desired.

Prepare marinade

In a bowl combine 3 tbs olive oil, 2 tbs Worcestershire sauce, 1 tbs Dijon mustard, 1 tbs apple cider vinegar, 3 tsp minced garlic, 1 tsp smoked paprika, 1.5 tsp salt and 1 tsp freshly ground black pepper. Whisk until smooth.

Marinate

Place turkey in a shallow dish or resealable bag and pour marinade over. Massage to coat thoroughly, cover and refrigerate for at least 30 minutes and up to 4 hours.

Breading and Frying (for assembly base)

Prepare breading stations

Set out three shallow bowls: one with 1 cup flour seasoned with 1/2 tsp salt and 1/2 tsp pepper, one with the beaten eggs mixed with 3 tbs milk, and one with 1.5 cups breadcrumbs.

Bread the turkey

Remove turkey from marinade and let excess drip off. Dredge each piece in seasoned flour, shake off excess, dip into egg wash, then press into breadcrumbs to coat evenly. Repeat for all pieces; press crumbs firmly so they adhere.

Shallow fry

Heat 1 cup vegetable oil in a large skillet over medium-high heat until shimmering (about 350°F / 175°C). Fry breaded turkey pieces in batches, 3–4 minutes per side, until golden brown and internal temperature reaches 165°F (74°C). Transfer to a wire rack set over a baking sheet to drain and keep warm in a low oven (200°F / 95°C) if needed.

Open-Face Bread Base and Assembly

Toast the bread

Preheat oven broiler or set oven to 425°F (220°C) for broiling. Arrange 6 slices of thick-cut bread on a baking sheet; brush lightly with a little olive oil or melted butter if desired. Toast under broiler or in oven until just golden on edges, about 1–2 minutes under broiler or 5–7 minutes at 425°F.

Assemble horseshoe

Place one fried turkey cutlet on top of each slice of toasted bread (if cutlets are larger than bread, fold slightly or use 1 cutlet per 2 slices). Generously sprinkle a mix of cheddar and mozzarella (about 1/2 cup cheddar + 2 tbsp mozzarella per sandwich) over the turkey. Add optional tomato slice on top of cheese and return to oven on broil/425°F for 2–4 minutes until cheese is fully melted and bubbly. Keep an eye to prevent burning.

Finish toppings

Remove from oven and scatter sliced green onions and chopped parsley over each open-faced sandwich.

Gravy

Make roux

While turkey is frying or toasting, melt 3 tbs unsalted butter in a medium saucepan over medium heat. Whisk in 3 tbs flour and cook, whisking constantly, for 1–2 minutes until bubbly and lightly blonde (do not let it brown).

Add stock and season

Slowly whisk in 3 cups turkey or chicken stock a little at a time to prevent lumps. Continue whisking until smooth. Add 1 tsp Worcestershire sauce and 1/2 tsp soy sauce if using. Bring to a simmer and cook 3–5 minutes until thickened to a gravy consistency. Taste and season with salt and black pepper to taste.

Strain (optional)

If you want a silky gravy, strain through a fine-mesh sieve into a warm container.

To Serve

Arrange two open-faced Turkey Horseshoes on each serving plate (three slices of bread total per plate if serving 3 people, or adjust to portion size). Generously ladle hot gravy over the cheese-covered turkey and bread so it soaks slightly into the bread.

Garnish with additional chopped parsley and extra sliced green onion. Serve immediately while hot.