Prepare the Herb Rub Paste:

1. In a small bowl, combine the olive oil, garlic powder, crushed oregano, black pepper, and salt. Stir into a paste and set aside.

Char the Garlic:

1. Heat a small cast iron skillet over medium-high heat. Place the unpeeled garlic cloves in the dry skillet.
2. Toast for 4-6 minutes, turning occasionally, until the skins are charred and fragrant.
3. Remove the cloves from the skillet and allow them to cool. Once cool enough to handle, slip off the skins and finely mince or mash the softened garlic. Set aside.

Toast & Assemble the Stuffing:

1. Wipe the skillet clean and return to medium heat. Add the dry panko breadcrumbs and toast, stirring constantly, until golden brown (1-2 minutes, watch closely as they burn easily).
2. Drizzle 1 tablespoon of olive oil over the crumbs and toss to coat.
3. Add the chopped baby spinach, salt, pepper, and a second tablespoon of olive oil. Cook for about 1 minute or just until the spinach wilts.
4. Remove the skillet from the heat immediately to prevent burning.
5. Fold in the mashed charred garlic, chopped parsley, grated Romano cheese, and the final tablespoon of olive oil. Stir until well combined. Transfer the stuffing to a bowl to prevent the cheese from sticking to the hot pan.

Stuff the Pork Roast:

1. Preheat your oven to 350°F (175°C). Line a large cast iron skillet with parchment paper.
2. Place the pork roast on a clean cutting board. Using a sharp knife, find the natural seams between the muscles and wedge them open with the knife. These are natural pockets between flaps of muscle meat, as well as between the muscle meat and marbling. Many of these seams should run the length of the pork roast, while others will be of varying depths. We are only looking to stretch or open the seams, not to slice through the pork.
3. Once the seams are open, stuff each resulting pocket thoroughly.
4. Once the pockets are stuffed, assess whether or not the pork is holding its shape. If the pork is not holding its shape, or if you are uncertain, secure the pork shut with a few strands of butcher’s twine.

Season and Bake:

1. Rub the prepared herb rub paste evenly over all exterior surfaces of the pork roast.
2. Place the stuffed roast into the parchment-lined large cast iron skillet.
3. Roast in the oven at 350°F for 20-25 minutes per pound (roughly 70-80 minutes total). Begin checking internal temperature at the 60-minute mark.
4. Remove the roast from the oven when an instant-read meat thermometer inserted into the thickest part of the meat (avoiding the stuffing) reads 140°F-142°F.

Rest and Serve:

1. Transfer the roast to a cutting board and let it rest loosely tented with foil for 8-10 minutes. Carryover heat will bring the internal temperature up to the safe minimum of 145°F while keeping the meat juicy.
2. Snip and remove the butcher’s twine. Slice into thick portions and serve warm with pan juices.