In a medium bowl, combine the butter, rosemary and minced garlic. Spoon the butter onto a piece of plastic wrap. Using the plastic wrap to keep your hands clean, roll the butter into a log about 2-1/2 inches long by 1-1/2 inches wide. Wrap it and freeze.

Remove the steaks from the refrigerator and let them rest at room temperature for 20 minutes.

In a small bowl, combine the salt, black pepper and garlic powder. Sprinkle about one teaspoon of the mixture on each steak, covering all sides.

Setup your grill for two-zone grilling with direct heat and indirect heat. If using a gas grill, turn half of the burners on high and leave the other half off. If using a charcoal grill, push the coals to one side.

Brush the grill grates with oil, so the meat won't stick. Then, place the filets on the grill over direct heat. Grill for 3 minutes. Rotate the steak a quarter turn to create cross hatch grill marks. Grill for 3 more minutes. Flip. Grill for 5 minutes.

Move the filets to the other side of the grill over indirect heat. Remove the butter from the freezer and cut into six equal slices. Top each filet with a pat of garlic rosemary butter.

Continue grilling to your desired doneness. You can check the temperature with a grill thermometer. Rare = 125F, Medium Rare = 135F, Medium = 145F, Medium Well = 150F, Well = 160F.

Remove to a plate and let rest for 10 minutes before serving.