Mix mushrooms, shallots, garlic and thyme in a food processor. Next, heat oil and butter in pan then add mushroom mixture to sautee until all the liquid has evaporated. Then season with salt and pepper.

Brush beef with oil and season then sear all sides in hot pan over high heat. Then remove from pan and coat beef with mustard on all sides.

Lay ou a double layer of cling wrap larhe enough to roll beef with. Lay slices of prosciutto on cling so that it can be rolled and encompass all of the beef.

Spread the duxelle mixture on top of the prosciutto. Then place beef on top of the duxelle. Next roll the beef so that the prosciutto wraps all around the beef. Roll it tight and then twist tie the ends. Chill in fridge for 30 minutes.

Preheat oven to 425°F.

Beat egg and mix with water to make egg wash.

Roll out pastry. Remove beef from fridge and cling wrap. Place beef in center of pastry. Fold over one side length wise. Brush edge with egg wash and the fold over other side length wise. Trim pastry as needed. Then brush edges on the ends with egg wash and seal the beef inside the pastry completely. Brush top of pastry with egg wash. Score the top of the pastry slightly. Sprinkle top with coarse salt if you desire.

Bake for 35-40 mins then let cool for 5-10 outside of oven.

Slice then serve with your favorite vegetable.