Slice tenderloin lengthwise cutting almost all the way through, but not quite. Place open tenderloin between two sheets of plastic wrap and pound with a meat mallet until tenderloin is about ½-inch thick.
In a large skillet over medium high heat, brown sausage until cooked through, about 10 minutes. Drain and cool.
Boil a large pot of water. Add broccoli rabe and cook for 6 minutes, then blanch in ice water to stop the cooking. Drain, then chop.
Toss broccoli rabe with sausage, peppers, and ricotta cheese. Mix well.
Stuff tenderloin with sausage mixture, spreading evenly across the entire tenderloin. Roll tenderloin, starting from the long side. Secure with twine every inch or so to keep the tenderloin rolled.
Toss together thyme, rosemary, parsley, oregano, salt, and pepper. Coat tenderloin with seasonings.
Bake tenderloin for 20–25 minutes (or until internal temperature reaches 155ºF).
Let cool for 5 minutes, then slice into medallions and top with shaved parmesan.