Preheat the oven to 425°F (220°C).

Season the beef tenderloin generously with salt and pepper.

In a large skillet, heat olive oil over high heat. Sear the beef on all sides until browned. Remove and let it cool.

Mushroom Duxelles:

In the same skillet, add chopped mushrooms, garlic, and thyme. Cook until the mushrooms release their moisture and become golden.

Pour in the white wine, scraping any browned bits from the bottom. Continue cooking until the liquid evaporates. Allow the mushroom mixture to cool.

Assembling:

Roll out the puff pastry on a floured surface to a size that will cover the beef.

If using foie gras or pâté, spread it over the cooled beef. Then, spread the mushroom mixture over the foie gras or pâté.

Brush the beef with Dijon mustard.

Place the beef in the center of the puff pastry and wrap it, sealing the edges. Brush the pastry with the beaten eggs.

Baking:

Transfer the wrapped beef to a baking sheet.

Bake in the preheated oven for about 25–30 minutes or until the pastry is golden brown.

For medium-rare beef, aim for an internal temperature of 130°F (54°C). Adjust the cooking time based on your desired doneness.

Resting and Serving:

Allow the Beef Wellington to rest for 10 minutes before slicing.

Serve the slices on plates, showcasing the layers of mushroom duxelles, flaky pastry, and succulent beef.

Optional Wine Sauce:

For an extra touch, make a red wine reduction sauce by deglazing the mushroom skillet with red wine, then simmering until reduced. Drizzle over the sliced Beef Wellington.