Defrost pastry dough if frozen.

Pre-heat oven to 425°F.

Rub beef tallow over tenderloins and place in a casserole dish.

Bake tenderloins for 15-20 minutes, allow to cool, and set aside juices for gravy later.

Melt 2 tablespoons butter in a pan and sauté mushrooms, onions, and garlic for 10 minutes; salt to season and remove from heat allowing to cool.

With remaining 2 tablespoons butter, melt and mix well with pâté in a separate bowl.

On a cutting board, sprinkle flour and lay out pastry dough.

Roll out dough into a rectangle of approximately 9x14" and ¼-inch thick.

Place tenderloins together in the center of the dough.

Spread pâté and then mushroom mixture on top of tenderloins.

Carefully wrap tenderloins with dough, pinching seams together, and place in casserole dish with seam side down.

Cut some slits across the top and brush with egg yolk.

Bake in oven for 25-30 minutes until pastry is golden brown. Test with thermometer; temperature should be between 120 to 130°F for medium rare.

In frying pan, combine tenderloin juices, broth, and wine on medium heat, and simmer for 10-15 minutes to reduce.