Chop rosemary and cut garlic into thin slivers. Cooking a Butterball turkey breast in a Crock-Pot is a convenient way to make a moist, tasty dish. Turn the wings back to hold the neck skin in place. Prep: Preheat oven to 350 degrees F while you are preparing the roast. Allow about six hours for the turkey to cook on low setting. Stuff with Garlic. Place turkey breast side up on a flat rack in a shallow roasting pan 2 to 2½ inches deep. How to Roast a Turkey Breast 1. Stuff with garlic: Stick garlic slice into each hole until you run out of garlic. Make holes in the roast: In a medium roasting pan or Dutch oven, place turkey roast and make 10-15 inserts with a paring knife.