Generously season the beef tenderloin with salt and black pepper. In a hot pan with olive oil, sear the beef on all sides until it develops a beautiful brown crust, about 2-3 minutes per side. Let it cool completely on a plate.

In the same pan, add the finely chopped mushrooms, minced shallot, and minced garlic. Sauté over medium heat until the mixture is dry and any excess moisture has evaporated, around 10-15 minutes.

Once the beef has cooled, brush a layer of Dijon mustard evenly over the surface. This adds a zesty flavor that beautifully complements the meat.

Lay out the slices of prosciutto on a clean surface, slightly overlapping. Spread the cooled mushroom mixture evenly over the prosciutto, then place the beef on top. Roll it up tightly, ensuring the beef is enclosed.

Place the wrapped beef in the fridge for 15–20 minutes. This helps it hold its shape and makes it easier to wrap in pastry.

Roll out the thawed puff pastry and place the wrapped beef in the center. Fold the pastry over the beef, sealing the edges tightly. You can use a little water to help the pastry stick together.

Prepare an egg wash by beating the egg, then brush it generously over the puff pastry to achieve a beautiful golden color while baking.

Preheat your oven to 400°F (200°C). Place the wrapped Beef Wellington on a baking sheet and bake for about 25-30 minutes, or until the pastry is golden brown and the beef reaches your desired doneness.

Once baked, let the Beef Wellington rest for 10 minutes. This allows the juices to redistribute. Slice and serve to reveal its stunning layers!