Heat your oven to 350 degrees. Then slice the shallots. Very finely chop 2 tablespoons of the shallot. Combine the finely chopped shallots with 1 tablespoon butter, the mustard, thyme, garlic, salt, and pepper to make the rub for the pork.

Getting the rub to stick on the beef might be a little challenging. I think patting the beef dry with a paper towel helps a bit. Evenly spread the rub on top of the beef coating all sides. Set aside.

Melt the remaining butter in a dutch oven (or similar) over medium heat. Add the mushrooms and sprinkle them with salt and pepper. Let cook for 2 minutes, and add the red wine, and let cook for another 3 minutes. Add the shallots and cook for an additional 3 minutes. Then pour the mushrooms and shallots into a bowl and set aside.

Increase the heat to high, and use the same dutch oven. Once it is hot, add the beef. You want to both brown the beef, while also preventing any drippings from burning. As the beef cooks, add beef broth to the pan as necessary, and loosen any browned bits from the pan. (This process helps to make the gravy even more delicious). Once all the sides of the beef tenderloin has browned (this takes about 4 minutes a side), add the mushrooms and shallots back into the pan. Add 1 cup of beef broth to the pan. Then place the lid on the pot, and place it in the oven to roast for 35-45 minutes, until the beef reaches 120-125 degrees. Remember the beef with increase in temperature another 15 degrees while it rests.

Remove the beef from the pan and let it rest on a cutting board while you finish the sauce.

Heat the mushrooms, shallots, and all of the juices over medium-high heat and bring to a simmer. Whisk in the flour, and the cream. Let simmer and reduce for 3 minutes.

Keep the sauce warm until the beef has rested for 10 minutes. Slice the beef and serve it with the mushroom shallot gravy.