Preheat the oven to 400°F. Spray a 9x13 dish with cooking spray and set it aside.
Pat the tenderloin dry with a paper towel and set it aside.
In a small bowl, combine the remaining ingredients and mix together.
Sprinkle the rub mixture on all sides of the tenderloin making sure it's fully covered.
Place the tenderloin in the baking dish.
Top the tenderloin with the small cubes of butter.
Bake the tenderloin in the oven for 25-30 minutes, just until the internal temperature reaches 145°F for medium-rare or 160°F for medium. The meat will continue to cook for a little bit once it's been removed from the oven so be sure to keep that in mind.
Remove the tenderloin from the oven and set it aside to rest for 10 minutes.
Slice the tenderloin and enjoy!
Video
Notes
The pan juices make an excellent gravy to serve over the tenderloin and potatoes.