Creating Classic Beef Chateaubriand can be straightforward if you follow these steps:

1. Preheat the Oven: Preheat your oven to 400°F (200°C).
2. Prepare the Beef: Season the beef tenderloin generously with salt and black pepper on all sides.
3. Sear the Beef: In a large oven-safe skillet, heat the olive oil over medium-high heat. Once hot, add the beef and sear for about 3-4 minutes on each side until browned.
4. Add Flavor: Add the butter, minced garlic, and herbs (if using) to the skillet. Baste the beef with the melted butter for added flavor.
5. Transfer to Oven: Place the skillet in the preheated oven and roast for about 15-20 minutes, or until the internal temperature reaches 130°F (54°C) for medium-rare.
6. Rest the Meat: Remove the skillet from the oven and transfer the beef to a cutting board. Let it rest for 10 minutes before slicing.
7. Prepare the Sauce: While the beef rests, make the sauce. Pour the red wine into the skillet, scraping up the browned bits from the bottom. Bring to a simmer and reduce by half.
8. Finish the Sauce: Stir in Dijon mustard and heavy cream (if using) for a richer sauce. Season to taste with salt and pepper.
9. Slice the Beef: Once rested, slice the beef tenderloin into thick medallions.
10. Serve: Plate the sliced beef and drizzle with the sauce.

These steps will guide you in creating this incredible dish effortlessly.