# What You Need:
→ Beef
01 - 6 beef tenderloin medallions, 2–3 oz each, about 1½ in thick
02 - Salt, to taste
03 - Freshly ground black pepper, to taste
→ Mushroom duxelles
04 - 8 oz cremini or button mushrooms, finely chopped
05 - 1 small shallot, finely minced
06 - 2 garlic cloves, minced
07 - 2 tablespoons unsalted butter
08 - 1 tablespoon fresh thyme leaves, chopped
09 - Salt and freshly ground black pepper, to taste
→ Assembly
10 - 1 sheet all-butter puff pastry (about 14 oz), thawed if frozen
11 - 3 oz thinly sliced prosciutto
12 - 1 large egg, beaten (for egg wash)
13 - All-purpose flour, for dusting
# How to Make It:
01 - Preheat the oven to 400°F and line a baking sheet with parchment paper; lightly flour a work surface.
02 - Pat medallions dry and season both sides generously with salt and freshly ground black pepper.
03 - Heat a heavy skillet over high heat and add a small amount of oil; sear each medallion 1 minute per side until browned but still rare inside; transfer to a plate and cool completely.
04 - In the same skillet over medium heat, melt the butter, add shallot and garlic and sauté 1 minute; add chopped mushrooms and thyme, season with salt and pepper and cook, stirring occasionally, until all moisture evaporates and mixture is dry, about 8 minutes; remove from heat and cool completely.
05 - Roll out the puff pastry on the floured surface to about 1/8 inch thickness and cut into six squares large enough to fully enclose each medallion.
06 - Place a slice of prosciutto on each pastry square, spread a spoonful of cooled mushroom duxelles over the prosciutto, then set a cooled beef medallion on top.
07 - Fold the pastry up and over the medallion, trimming excess dough and pressing to seal; place each parcel seam-side down on the prepared baking sheet.
08 - Brush each parcel with beaten egg; use pastry scraps to add decorative shapes if desired and brush decorations with egg wash as well.
09 - Bake 18–20 minutes until pastry is golden brown and crisp; remove from oven and let rest 5 minutes before serving.