Defrost spinach in microwave. Wrap in clean kitchen towel and wring chopped spinach dry.
Place a large skillet on the stove over medium high heat. Add 2 tablespoons extra-virgin olive oil-to hot skillet. Add garlic to oil. Add onion and red pepper, cook 1 minute. Lower heat to medium. Add the prosciutto and the spinach. Season with salt and pepper. Add bread crumbs and cheese to spinach. Turn off heat. Let stuffing cool.
To create the cavity for the stuffing, use a long sharp knife (like a boning knife), and cut a 1 to 2-inch hole through the center of the roast making a lengthwise slit. Turn the meat around and cut another slit in the same spot so that your knife completes the cavity. Insert a wooden spoon into the cavity to make sure the hole is even and goes all the way through.
Put the cooled filling in a re-sealable plastic bag and snip a hole in the corner of the bag. Pipe the filling into the cavity. You may need to push it along with your fingers to make sure that it goes all the way through.
Preheat nonstick skillet over high heat. Cut the roast into 6 even slices, being careful to keep the stuffing in each slice. Add 2 tablespoons of extra-virgin olive oil to the pan. Season the steaks with salt and pepper and sear in hot, nonstick skillet, 2 minutes on first side. Flip the steaks and sear for an additional 2 minutes then lower the heat to medium-high and cook until done (about 3 to 4 more minutes). Garnish with thinly sliced red pepper.