• 1 pound mixed mushrooms (whatever the store has, the earthier the better, regular white ones just won't do)

• 1/4 cup grated parmesan cheese

• 2 sticks butter

• 2 packages fresh spinach

• 1/2 cup flavored breadcrumbs

• Salt, Pepper, Oregano, Thyme to taste

Trim the fat off the tenderloin or have the butcher do it for you. Make a slit 3/4 of the way through the meat lengthwise starting 1 1/2 inches from one end and ending 1 1/2 inches from the other. Rub some kosher salt and fresh ground pepper into the meat.

Melt a stick of the butter in a very large fry pan. Slice 3/4 of the mushrooms into large pieces and cook in the butter until tender. Remove from the pan.

Rinse and drain one package of the spinach. Over high heat put in the large fry pan, cover either with another fry pan or a cover. Cook a couple of minutes until wilted, remove from heat and drain. Repeat with the other package of spinach. Squeeze the water out of it.

Coarsely chop the spinach, add to the cooked mushrooms. Add the cheese, spices, and 1/4 of the bread crumbs. Mix by hand until it starts to hold its shape. Stuff into the meat, letting it stick out about an inch. Tie the meat with string to keep it closed.

Roast in a 400 degree oven for 30 minutes. Melt 1/2 stick of butter, add the remaining 1/4 cup of bread crumbs and place as a topping on the stuffing. Return to the oven for another 15 minutes (check for desired doneness with a thermometer) . Remove and let stand for 15 minutes before removing the string and slicing.

Sauté the remaining mushrooms (sliced thin) in a bit of butter, set aside. Make a dark Roux of 2 tablespoons butter and 2 tablespoons flour (Roux - Heat the butter and flour over medium high heat until the flour is cooked to the desired color). Remove from heat.

Add 1/4 cup red wine to the roasting pan and scrape to remove the juices. Leave any bits of stuffing that fell in for the gravy. Pour into a large measuring cup. Raise the liquid in the cup to two cups by adding either chicken or beef broth or water.

Add the liquid to the roux mix (watch for splattering), and start stirring. Add the sautéed mushrooms, cook on medium stirring constantly until it boils. Remove from heat and serve warm.