Preheat Oven: Set your oven to 425°F (220°C) for a beautifully roasted tenderloin.
Prepare Stuffing: In a mixing bowl, combine breadcrumbs, minced garlic, chopped onion, melted butter, and chopped parsley.
Prep Tenderloin: Carefully slice the beef tenderloin lengthwise into a pinwheel shape, taking care not to cut all the way through, then gently unroll it.
Stuff Tenderloin: Spread the prepared stuffing mixture evenly over the opened tenderloin.
Secure Roll: Roll the tenderloin tightly and tie with kitchen twine at 1-inch intervals.
Season: Generously season the outer surface with salt and pepper.
Roasting: Place the stuffed tenderloin in a roasting pan and roast for 50-70 minutes, aiming for 145°F for medium-rare.
Resting Period: Remove from oven, cover with foil, and let rest for 15-20 minutes before slicing.
Notes
For best results, use quality beef and pay attention to cooking times for desired doneness.