Add mushrooms, salt, and pepper to a food processor and process until they are finely minced, forming a rough paste.

In a medium sauté pan over medium heat, add the mushroom paste. Spread the mixture equally over the surface and cook on medium heat until the moisture in the paste mostly evaporates for 15–20 minutes. Remove from heat, stir in the chives, and let cool. The mixture has the consistency of a spreadable pâté.

Sear the Beef Tender Filet.

With paper towels, pat dry filet mignon, then season liberally with salt and pepper. Heat a skillet over medium-high heat and add oil. While the oil is hot but not smoking, add the filet mignon and brown for 1–2 minutes on all sides. Remove from heat and position on a cutting board. Brush Dijon mustard onto the filet and allow it to cool.

Put the a-sided baking sheet in the oven and preheat the oven to 425°F.

On a cutting board, lay out a long piece of plastic wrap. In the middle of the wrap, lay out the prosciutto shingle-style to form a large rectangle sufficient to encompass the whole filet. Then, smeared mushroom duxelles are placed in a thin layer over the prosciutto. Place the filet on top of the mushrooms. Utilize the plastic wrap to help roll the beef up tightly in the duxelles-covered prosciutto, tucking in the ends so the beef has fully encompassed. Refrigerate for 20 minutes.

In a bowl, mix egg yolk and milk.

Tenderly roll out the puff pastry on a floured surface until it is ¼ inch thick, no thinner. Depending on the pastry sheet's size, The two overlapping layers of the dough can be used to ensure the filet is completely covered and sealed. Set the beef in the center of the pastry and liberally brush the pastry with the egg wash. Bring puff pastry up and around the beef and seal tightly. Steal the ends closed and trim off any excess puff pastry. Refrigerate for 5–10 minutes to let it firm up again.

Remove Wellington from the refrigerator. Put the Wellington seam side down on the preheated baking sheet. Brush the top of the puff pastry with the leftover egg wash and score it with a sharp paring knife. Sprinkle with sea salt and place the pan in the oven.

Bake for about 35 minutes or until the steak's internal temperature reaches 120°F for medium-rare.

Remove from the oven and rest for at least 10 minutes before slicing.

Place the blackberries, red wine, and stock in a heavy-based saucepan and bring to a boil. Cook for about 5 minutes until the blackberries have softened.

Strain the mixture through a fine-mesh strainer and discard the seeds and pulp. Return the sauce to the saucepan over medium-high heat, add the honey and jam, and boil until the mix reduces by half and thickens to a smooth sauce. Remove from the heat, swirl in the butter season to taste, and set aside to keep warm.

Place the potatoes in a large saucepan and cover with cold water by two inches. Add ½ teaspoon salt and bring to a boil. Reduce the heat to simmer, cover the pot partially, and cook until the potatoes are very tender when tested with a sharp paring knife tip, 20 – 25 minutes.

Drain the potatoes, saving some of the cooking water.

Combine the cream and butter in a small saucepan over medium heat and simmer.

Put the potatoes through a potato ricer or food mill and return them to the pot over low heat. Combine the hot cream and butter mixture and mix with a wooden spoon. If the potatoes are too thick, add a small amount of the reserved cooking water until the texture you like the season tastes with salt and pepper and set aside to keep warm.

Bring a quart of salted water to a boil. Have a bowl of iced water ready.

In a large sauté pan, melt the butter over medium heat. Then add the carrots and cook for about 4 minutes until they are crisp-tender. Utilize a slotted spoon to transport the carrots to the bowl of ice water to stop the cooking, then drain. Combine the carrots and toss to coat; cook until heated thoroughly. Mix in the parsley and season to taste with salt and pepper.