Chef John's Individual Beef Wellingtons

Melt butter over medium-high heat in a skillet. Add mushrooms and salt; cook, stirring occasionally, until deeply browned and caramelized (about 5 minutes). The mushrooms will initially release moisture but will eventually dry out and brown.

Add shallots to the skillet and cook until softened and translucent (about 3 minutes). Stir in black pepper, cayenne, and white wine. Cook until the wine has evaporated completely (about 1 minute). Remove from heat and transfer the mixture to a bowl to cool completely.

Once the mushroom mixture has cooled, incorporate the pate. Use a spoon to thoroughly combine the pate with the mushrooms, ensuring a smooth, even consistency. Set aside.

Generously season the filet mignon steaks with salt and pepper. In the same skillet, melt butter over high heat. Sear the filets, one at a time, until all sides and edges are deeply browned (about 5 minutes per filet). Transfer the seared filets to a plate and chill in the refrigerator until ready to assemble.

On a lightly floured surface, cut each sheet of puff pastry into 4 equal squares. Take one square of puff pastry and spoon approximately 3 tablespoons of the mushroom pate mixture into the center. Gently spread the pate to roughly the same size as a filet. Spread 1/2 tablespoon of Dijon mustard on top of one filet and place mustard-side down onto the pate-covered pastry.

Carefully stretch and fold the shorter sides of the pastry around the filet, then bring the longer sides up and over to seal the Wellington. Avoid over-stretching the pastry on the sides and top; some small holes at the bottom are acceptable. Flip the Wellington over so that the seam is facing down and place it on a plate. Repeat this process to form the remaining 3 Wellingtons, then transfer all to the refrigerator to chill.

Preheat the oven to 425 degrees F (220 degrees C). Line a baking sheet with parchment paper.

Cut the remaining 4 squares of puff pastry into circles that are slightly larger than the base of the Wellingtons. Place these circles on the prepared baking sheet and use a fork to prick them all over to prevent excessive puffing.

Bake the pastry bases in the preheated oven for 15 minutes. Remove from the oven, flip the circles, and gently press them down with a spatula to flatten. Return to the oven and bake until golden brown and crispy (5 to 10 minutes longer). Remove from the oven and transfer to a wire rack to cool.

Increase the oven temperature to 450 degrees F (230 degrees C). Place the assembled Wellingtons in the freezer for exactly 15 minutes to help them firm up before baking.

Line the same baking sheet with aluminum foil, then top with parchment paper. In a small bowl, whisk together the egg and water to create an egg wash.

Remove the Wellingtons from the freezer after 15 minutes and transfer them to the prepared baking sheet. Generously brush the tops and sides of each Wellington with the egg wash.

Bake the Wellingtons in the center of the preheated oven until the pastry is golden brown and puffed and the filets are cooked to your desired doneness (23 to 25 minutes). An instant-read thermometer inserted into the center of the filet should read 122 degrees F (50 degrees C) for medium-rare.

Remove the Wellingtons from the oven and let them rest on a plate or cutting board for at least 5 minutes before serving. Cut each Wellington in half and trim each end to create a flat, even surface.

To assemble the final dish, place a baked pastry base on each plate. Stand two filet halves on top of the pastry base, with the center cut facing upwards, to showcase the perfectly cooked interior.