Puff Pastry Beef Wellington

Preheat a heavy skillet over extremely high heat until it reaches scorching temperatures. Sear the filets on both sides until they achieve a deep, rich brown color, approximately 1 to 2 minutes per side. Remove the filets from the skillet and allow them to cool slightly before refrigerating them for at least one hour. It is crucial that the filets are chilled.

In the same skillet, adjust the heat to a moderate level and melt butter. Cook and stir the mushrooms, shallots, and garlic until the shallots become tender and translucent, while the mushrooms release their natural juices, taking around 6 to 8 minutes. Stir in two tablespoons of wine and scrape any browned residue from the bottom of the pan to prevent it from forming a stubborn layer. Transfer the mushroom mixture to a bowl, cool slightly, and refrigerate for approximately 45 minutes.

Place two pieces of puff pastry on a flat surface. Top each piece with a chilled filet, followed by half the mushroom mixture layer on top of the filet. Cover each with a piece of puff pastry, then fold and pinch the edges together to seal in the ingredients. Trim any excess pastry to create a neat package, and cut a small slit on top of each bundle.

Pour the remaining 1.5 cups of red wine into a saucepan over medium heat, and let it simmer until the wine has reduced by half, taking around 15 minutes. Season to taste with salt and pepper, then set it aside to keep warm.

Whisk together an egg and milk. Brush the pastry bundles with the egg mixture for a golden crust, if desired. Return the bundles to the refrigerator to keep them chilled.

Preheat your oven to 450 degrees Fahrenheit (230 degrees Celsius). Line a baking sheet with parchment paper.

Place the puff pastry bundles on the prepared baking sheet. Bake in the preheated oven until the pastry is golden brown and crispy, while the filets reach your desired level of doneness (approximately 15 minutes for medium-rare; use an instant-read thermometer to check the internal temperature, which should read 130 degrees Fahrenheit (54 degrees Celsius)). Serve each filet in its pastry shell, accompanied by a spoonful of warm wine sauce on top.