• Let the beef stand at room temperature for 30 minutes before roasting. Set an oven rack in the middle position and preheat the oven to 400°F.
• Melt 5 tablespoons of the butter in a medium saucepan. Add the shallots and cook over medium-low heat, stirring occasionally, until soft and translucent, 7 to 8 minutes. Add the wine, beef broth, thyme sprigs, ¼ teaspoon of the salt, pepper, and sugar, and bring to a boil. Cook over medium heat for about 30 minutes, or until the liquid is reduced by about half.
• Season the beef all over with remaining 2 teaspoons salt and pepper. Heat the oil in an oven-proof skillet over medium-high heat until almost smoking. Cook, turning with tongs until well browned on all but one side, about 10 minutes total. Turn the tenderloin so that the un-seared side is down, and transfer the skillet directly to the preheated oven. (If your pan isn't oven-proof, transfer the beef to a lightly oiled roasting pan.) Roast until an instant-read thermometer inserted into the center of the meat registers 120°F-125° for medium-rare, about 15 minutes, or until done to your liking (115°F-120°F for rare, 130°F-135°F for medium). Keep in mind that these temperatures account for the fact that the temperature will continue to rise about 5 degrees while the meat rests.
• While the liquid is reducing, place the remaining 3 tablespoons of butter in a small bowl and soften in the microwave, if necessary (it should be soft but not melted). Add the flour and, using a small spoon, mix into a smooth paste.
• Once the wine mixture is reduced, reduce the heat to low and remove the thyme sprigs. Whisk the flour-butter paste, a teaspoonful at a time, into the simmering liquid, and simmer for a few minutes, until the sauce is thickened. Set aside. (The sauce can be made up to this point and refrigerated up to 3 days ahead of time.)
• Transfer the meat to a carving board (preferably with a well for collecting juices) and let it rest, covered loosely with aluminum foil, for 10 to 15 minutes. Place a dish towel or oven mitt over the handle of the roasting pan to remind yourself that it's hot.
• Meanwhile, carefully discard the fat from the roasting pan (remember that the handle is hot!). Set the pan on the stovetop and add the 1/4 cup of beef broth. Bring the broth to a boil, using a wooden spoon to scrape the fond, or brown bits, from the bottom of the pan. Add the flavorful broth to the red wine sauce, and then bring the sauce to a simmer.
• Carve the tenderloin into 1/3-inch-thick slices. Serve the beef, passing the red wine sauce at the table.

Preheat Oven:

• Preheat the oven to 400 degrees F. (200 degrees C).

Cream Cheese Mixture:

• In a mixing bowl, combine the room temperature cream cheese, thawed and drained spinach, and shredded cheese. Mix until all of the ingredients are well incorporated. Season this mixture with a pinch of salt and pepper to taste. Set the filling aside.

Puff Pastry:

• On a lightly floured surface, roll out the thawed puff pastries sheets into a rectangle.
• Place half of the the cream cheese mixture in the center of each of the puff pastry, leaving some space around the edges.
• Lay the salmon fillets on top of the cream cheese mixture, centered within the puff pastry.
• Season the salmon with salt and pepper to taste.
• Carefully, fold the puff pastry over the salmon and filling to encase it completely. Make sure to seal the edges by pressing them together firmly. Use a little water to help seal, if needed.
• Transfer the Salmon Wellingtons to a baking sheet lined with parchment paper, seam side down.
• Using a sharp knife, make a few slits on top of the pastry to allow steam to escape during baking. This will help prevent the pastry from getting soggy.
• In a small bowl, beat an egg to create an egg wash. Brush the top of the pastry with the egg wash to give it a nice golden color when baked.
• Place the baking sheet in the preheated oven, and bake for approximately 25-30 minutes or until the puff pastry is golden brown and the salmon is cooked to the desired level of doneness. The internal temperature of the salmon should reach 145 degrees Fahrenheit (63 degrees Celsius).
• Remove the Salmon Wellington from the oven, and let it rest for a few minutes before slicing and serving. Service with a lemon wedge.