Preheat your oven to 400F and move the rack to the middle position.
Prep the tenderloins by cutting off any excess fat and the silver skin (the tough part that may cover some of each tenderloin). Pat the tenderloins dry with paper towel.
Add the spice rub ingredients (brown sugar, smoked paprika, garlic powder, onion powder, chili powder, Italian seasoning, salt & pepper) to a small bowl and stir together. Coat the tenderloins all over with the spice rub.
Add the pork tenderloins to a 9×13 (or similar size) baking dish and place the butter pats on top.
Bake, uncovered, for about 25 minutes or until the pork has reached 145F. Let it rest 5-10 minutes before slicing it into medallions so it remains juicy.
Pour the pan juices over the pork (they're also great over a side dish like mashed potatoes) and sprinkle with chopped parley if desired.
Notes
Serves 6-8 depending on portion size. Halve all ingredients if you want to make one (one pound) pork tenderloin.This recipe is NOT for pork loin, which is a different, tougher cut of meat and will need to be cooked for longer.Pork that’s 145F in the thickest part is safe to eat. Use an instant-read meat thermometer to ensure perfect doneness.