2. Marinate the pork tenderloin for at least 30 minutes or up to 2 hours.
3. While the pork is marinating, melt the butter in a skillet and add the mushrooms, shallots, thyme, salt and pepper. Deglaze with white wine. Cook until the liquid has evaporated. Drain the mushrooms in a strainer. Stir in the bread crumbs.
4. Roll the mushrooms into 3 1/4-inch plastic wrap tubes the length of the cleaned tenderloin (about 6-7 inches). Wrap tightly and freeze.
5. Remove the tenderloins from the marinade and pat dry. Using a steel or the handle of a wooden spoon, make a hole in each tenderloin lengthwise. Tie the mushroom tube to a knitting needle or skewer and pull through until the mushroom roll is filling the tenderloin entirely.
6. Slice off the back end of the plastic wrap at the end of the tube not tied to the skewer. Hold the skewer end of the tenderloin closed and pull the plastic wrap from the inside of the tenderloin, leaving the mushrooms. Repeat this for the remaining tenderloins.
7. Season the pork tenderloin with salt and freshly cracked pepper. Sear on all sides in a dry hot pan and finish in a 350°F oven for 12 to 15 minutes.
8. Place the tenderloins on a cutting board and let them rest 2 to 3 minutes before slicing.