Preheat the oven to 350°F.

Heat 2 tbsp olive oil in a large skillet over medium-high heat. Sauté the onions and sauté until they begin to soften, about 5 minutes. Add the spinach and sauté until it is wilted down. Remove from heat and let cool.

Cut through pork tenderloin lengthwise so it can open up like a book. Using a meat mallet, pound out each side until it’s about ¼-inch thick. Distribute the spinach and onion mixture over tenderloin and top with the cheese. Roll tenderloin from the long side, and tie with string so it holds its shape. Sprinkle the outside with salt, pepper and Italian seasoning

Heat the remaining olive oil in an ovenproof skillet over medium-high heat. Add tenderloin and let it sear on all sides for about 5-6 minutes total. Place the skillet in oven. Roast the pork until a thermometer inserted into thickest part registers 150°F, about 35 minutes. Remove from oven and cover with foil to let the juices re-distribute and to rest.

Use the same skillet and place back over medium heat, and add the wine and broth. Boil until the sauce thickens, scraping up browned bits, about 10 minutes. Season with salt and pepper. Remove strings from the pork and cut into 1/2-inch-thick slices. Spoon the sauce over the pork.