If needed, trim excess fat from the beef cutlets. Place each cutlet between two sheets of plastic wrap and pound with a meat mallet or heavy pan to about 1/8–1/4 inch thickness. Lightly season both sides with 1/2 teaspoon salt and 1/4 teaspoon black pepper (portion of the salt/pepper listed in ingredients).

Set up breading station

Arrange three shallow dishes: one with the all-purpose flour, one with beaten eggs mixed with 2 tablespoons milk and a pinch of salt, and one with the breadcrumbs combined with 1/4 cup grated cheese, 1 teaspoon dried oregano, 1/2 teaspoon garlic powder, and remaining 1/2 teaspoon salt and 1/4 teaspoon pepper. Press breadcrumbs mixture together lightly so it will adhere.

Bread the cutlets

Working one at a time, dredge a cutlet in flour, shaking off excess. Dip into the egg mixture, then press firmly into the breadcrumb mixture so the cutlet is evenly coated. Place breaded cutlets on a wire rack or tray; let rest 5–10 minutes to set the crust.

Fry until golden

Pour about 1/2 to 3/4 cup vegetable oil into a large skillet to reach roughly 1/8–1/4 inch depth and heat over medium-high until shimmering (about 350°F/175°C) or a small breadcrumb sizzles on contact. Add breaded cutlets (do not overcrowd; cook in batches if necessary). Fry 2–3 minutes per side until golden brown and crisp. Transfer to a paper towel-lined plate or wire rack to drain. If cutlets are thicker than 1/8 inch, reduce heat slightly and cook a bit longer to ensure cooked through.

Make Napolitana topping and prepare rolls

Warm the sauce

Gently warm the marinara sauce in a small saucepan or microwave until hot but not boiling (about 2–4 minutes on medium heat). Taste and adjust with 1/4 teaspoon salt if needed and a few grinds of black pepper.

Prepare rolls

Preheat the oven broiler (or set oven to 400°F/200°C for toasting). Spread softened butter on cut side of each roll and, if desired, brush lightly with 1 teaspoon olive oil. Place rolls cut-side up on a baking sheet and toast under broiler 1–2 minutes until golden — watch carefully so they do not burn. Alternatively, toast in a skillet until lightly crisp.

Assemble and finish sandwiches

Top cutlets with sauce and cheese

Place one fried milanesa on a toasted roll bottom. Spoon about 2–3 tablespoons warm marinara sauce over each cutlet (enough to coat but not soak the crumb). Top with approximately 2 oz (about 1/4 cup) shredded or 2 slices of mozzarella per sandwich. If using fresh tomato slices, add one thin slice on top of the sauce before the cheese.

Melt the cheese

Place assembled open-faced sandwiches on a baking sheet and put under the broiler for 1–2 minutes, or until the mozzarella is melted and bubbling and edges of the breadcrumb are just warmed through. Alternatively, place in a 400°F/200°C oven for 4–6 minutes to melt the cheese.

Finish and serve

Remove from oven, add fresh basil leaves over the melted cheese (tuck a leaf under the cheese or place on top). Close sandwiches with toasted roll tops. Serve immediately while hot with extra marinara on the side for dipping.