Prepare the Herb Butter:

1. Make the Herb Butter: In a medium bowl, combine softened butter, minced garlic, chopped rosemary, chopped thyme, Dijon mustard, salt, and pepper. Mix until fully incorporated. This flavorful herb butter will coat the beef and keep it moist during roasting.

Prepare the Beef Tenderloin Roast:

2. Preheat the Oven: Preheat your oven to 450°F (230°C). Line a roasting pan or baking sheet with aluminum foil or parchment paper to catch any drippings.
3. Sear the Beef Tenderloin: Heat olive oil in a large skillet over medium-high heat. Once the oil is hot, sear the beef tenderloin roast for 2-3 minutes per side, until browned and caramelized. This step helps develop a rich flavor and ensures a beautifully crispy crust on the roast.
4. Apply the Herb Butter: Once the beef is seared, remove it from the skillet and transfer it to the prepared roasting pan. Generously spread the herb butter mixture over the entire surface of the roast, massaging it into the meat to coat it evenly.

Roast the Beef:

5. Roast in the Oven: Place the beef in the preheated oven and roast for 25-30 minutes for medium-rare (120-125°F internal temperature) or 35-40 minutes for medium (130-135°F internal temperature). Use a meat thermometer to check the internal temperature of the roast for your desired level of doneness. Keep in mind that the roast will continue to cook slightly after removing it from the oven.
6. Rest the Roast: Once the roast reaches your desired temperature, remove it from the oven and let it rest for 10-15 minutes. This allows the juices to redistribute and ensures the roast remains tender and juicy.

Slice and Serve:

7. Slice the Roast: After resting, slice the beef tenderloin roast into 1-inch thick slices, being careful to cut against the grain to maintain tenderness.
8. Serve and Garnish: Arrange the slices on a serving platter and garnish with chopped fresh parsley if desired. Serve the roast with your favorite sides, such as mashed potatoes, roasted vegetables, or a fresh salad.