Creating Beef Wellington is a process, but breaking it down into manageable steps makes it surprisingly approachable. Follow these instructions carefully, and you’ll be rewarded with a dish that’s both impressive and incredibly delicious.

1. Prepare the Beef Tenderloin: Remove the beef tenderloin from the refrigerator at least 30 minutes before cooking to allow it to come to room temperature. This ensures more even cooking. Pat the tenderloin dry with paper towels. Season generously on all sides with salt and freshly ground black pepper.
2. Sear the Beef: Heat olive oil in a large, oven-safe skillet (cast iron is ideal) over high heat until it shimmers. Sear the beef tenderloin on all sides, including the ends, until nicely browned, about 2-3 minutes per side. This step is crucial for developing flavor and sealing in juices. Don’t cook it through, just sear the exterior. Remove the seared tenderloin from the skillet and let it cool slightly.
3. Make the Duxelles: While the beef cools, add butter to the same skillet (no need to wipe it out, the beef fond will add flavor). Add finely chopped shallots and sauté over medium heat until softened and translucent, about 3-4 minutes. Add minced garlic and cook for another minute until fragrant. Increase heat to medium-high, add the finely chopped cremini mushrooms, and cook, stirring frequently, until the mushrooms release their moisture and it evaporates, and they begin to brown and caramelize. This process can take 15-20 minutes, be patient and let the moisture cook out – this is key to a non-soggy Wellington.
4. Deglaze and Finish the Duxelles: Pour in the dry sherry or white wine to deglaze the pan, scraping up any browned bits from the bottom. Cook until the liquid is almost completely evaporated. Stir in the chopped fresh thyme, salt, and pepper to taste. Cook for another minute to combine the flavors. Remove the duxelles from the heat and let it cool completely.
5. Prepare the Prosciutto Layer: Lay out a large sheet of plastic wrap on a clean work surface. Arrange overlapping slices of prosciutto in a rectangular shape on the plastic wrap, large enough to fully wrap around the beef tenderloin. Aim for a slightly larger rectangle than the circumference of your tenderloin.
6. Assemble the Wellington: Spread the cooled duxelles evenly over the prosciutto layer, leaving a small border around the edges. Ensure the duxelles is spread in an even layer for consistent flavor. Place the seared beef tenderloin on top of the duxelles-prosciutto layer, near one edge.
7. Roll and Wrap: Using the plastic wrap to help, tightly roll the prosciutto and duxelles around the beef tenderloin, forming a log. Twist the ends of the plastic wrap tightly to seal and shape the Wellington. Refrigerate the wrapped Wellington for at least 30 minutes, or up to 2 hours. This chilling step helps the Wellington hold its shape and makes it easier to work with the puff pastry.
8. Prepare the Puff Pastry: Lightly flour a clean work surface. Unfold the thawed puff pastry sheets. You may need to slightly roll out the puff pastry to create a large enough sheet to encase the Wellington. You want it large enough to fully enclose the beef and overlap slightly. If using two sheets, gently press the edges together to create one larger sheet.
9. Wrap in Puff Pastry: Remove the chilled Wellington from the refrigerator and unwrap it from the plastic wrap. Place the Wellington log in the center of the puff pastry sheet. Bring the puff pastry up and over the Wellington, encasing it completely. Trim away any excess pastry, leaving about an inch overhang. Crimp the edges of the pastry to seal the Wellington, ensuring a tight seal to prevent any leaks during baking. You can use a fork to create a decorative crimped edge.
10. Egg Wash and Score: In a small bowl, whisk together the egg and a tablespoon of water to create an egg wash. Brush the entire surface of the puff pastry with the egg wash. This will give it a beautiful golden brown color and shine. Using a sharp knife, gently score the top of the puff pastry in a decorative pattern. Be careful not to cut all the way through the pastry, just score the surface to allow steam to escape.
11. Chill Again (Optional but Recommended): For optimal puff pastry texture and to further prevent leaks, chill the assembled Wellington in the refrigerator for another 15-20 minutes before baking.
12. Bake the Wellington: Preheat oven to 400°F (200°C). Place the prepared Beef Wellington on a baking sheet lined with parchment paper (for easy cleanup). Bake for 35-45 minutes, or until the puff pastry is golden brown and cooked through. The internal temperature of the beef should reach 130-135°F (54-57°C) for medium-rare, or adjust to your desired level of doneness. Use a meat thermometer inserted into the center of the Wellington to check the temperature.
13. Rest Before Slicing: Once baked, remove the Beef Wellington from the oven and let it rest for at least 10-15 minutes before slicing. This allows the juices to redistribute, resulting in a more tender and flavorful Wellington. Tent loosely with foil while resting.
14. Slice and Serve: Carefully slice the Beef Wellington into thick slices, about 1-1.5 inches thick, using a serrated knife. Serve immediately and enjoy the culinary masterpiece you’ve created!