Preheat the oven to 400°F (200°C).

Prepare the roasted garlic by cutting the top off the head of garlic, drizzling it with a little olive oil, and wrapping it in aluminum foil. Roast in the preheated oven for 30-35 minutes, until the cloves are soft and caramelized. Allow to cool slightly, then squeeze the garlic cloves out of their skins and set aside.

In a shallow dish, combine the chopped toasted pecans, fresh thyme, salt, and black pepper. Press each beef medallion into the pecan mixture, ensuring an even coating.

In a large skillet, heat the olive oil over medium-high heat. Add the beef medallions and sear for 3-4 minutes on each side until browned. Remove the medallions from the skillet and set aside.

In the same skillet, add the butter and melt over medium heat. Stir in the flour and cook for 1-2 minutes until lightly browned.

Gradually whisk in the beef broth, stirring constantly. Add the roasted garlic and Worcestershire sauce, and continue to cook until the gravy thickens, about 5-7 minutes. Season to taste with salt and pepper.

Return the beef medallions to the skillet, spooning some of the gravy over the top. Reduce the heat to low, cover, and let simmer for an additional 5 minutes, allowing the medallions to absorb the flavors.

Serve the beef medallions topped with the silky roasted garlic gravy and garnish with fresh thyme sprigs.