Preheat your oven to 350°F (175°C).

In a mixing bowl, combine fresh chopped spinach, ricotta cheese, grated Parmesan, breadcrumbs, minced garlic, dried oregano, salt, and black pepper. Mix thoroughly.

Lay the flank steak slices flat on a clean surface.

Place a generous amount of the prepared filling at one end of each flank steak slice and roll tightly, securing with kitchen twine or toothpicks.

Heat olive oil in an oven-safe skillet over medium heat and sear the braciole on all sides for about 5 minutes.

Pour marinara sauce generously over the braciole in the skillet and cover to trap steam.

Transfer the skillet to the preheated oven and bake for 30-35 minutes.

Remove the skillet from the oven and allow the braciole to rest for about 5 minutes before serving garnished with fresh basil leaves.