Preheat your oven to 425°F (220°C). Gather your tools, including a roasting pan and a wire rack.

In a mixing bowl, combine breadcrumbs, minced garlic, diced onion, melted butter, and chopped parsley. Stir until all ingredients are well integrated.

Take your beef tenderloin and slice it lengthwise, flattening it out gently to create a surface for the stuffing.

Spread the stuffing mixture evenly over the entire surface of the sliced beef tenderloin.

Carefully roll the beef tenderloin tightly, securing it with butcher’s twine at 1-inch intervals.

Generously season the outer layer of the rolled tenderloin with salt and pepper. Place it in a roasting pan with a wire rack.

Roast the tenderloin in the preheated oven for approximately 50 to 70 minutes, checking the internal temperature with a meat thermometer.

Once the desired temperature is reached, remove it from the oven and let it rest for 15-20 minutes.

After resting, slice the tenderloin into 1-inch thick rounds and arrange on a serving platter.