Preheat oven to 350 degrees F (175 degrees C). Grease a baking sheet.
Mix green onions, bacon, Cheddar cheese, cream cheese, spinach, mushrooms, garlic, parsley, salt, and pepper in a bowl. Spread onto one side of pounded tenderloin. Roll tenderloin around the filling in a jelly-roll fashion. Coat rolled tenderloin with bread crumbs; place on the prepared baking sheet.
Bake in the preheated oven until pork is no longer pink in the center, about 1 1/2 hours. An instant-read thermometer inserted into the center should read at least 145 degrees F (63 degrees C).
Tie up the stuffed tenderloin with oven string. You might try just using all cream cheese (and extra) and mix it well with the other ingredients