In a small bowl, mix together the orange-rosemary butter ingredients. Use immediately or chill (bring to room temperature before using).
Preheat oven to 350°F.
With a knife, make slits in tenderloins and alternately insert garlic and orange peel slivers.
In a large skillet over medium heat, melt 2 Tablespoons of the butter mixture and brown tenderloins evenly for 5-10 minutes.
Place tenderloins on rack in roasting pan. Spread a teaspoon of flavored butter over each tenderloin.
Add broth to skillet drippings and stir. Pour broth/drippings into the roasting pan and roast uncovered for 20 minutes.
Spread another teaspoon of flavored butter over each tenderloin and roast an additional 15-20 minutes or until center of tenderloin registers 155°F (use meat thermometer).
Transfer pork to serving platter and cover loosely with foil. Temperature of meat should increase to 160°F while standing.
Pour liquid from roasting pan back into skillet and bring to a boil, cooking until reduced by half. Whisk remaining flavored butter into liquid and simmer about 3 minutes, stirring constantly. Season with salt and pepper.
To serve, slice pork and drizzle with sauce.