1: Preheat oven to 325 degrees.
2: Carefully separate skin from the breast using a large spoon while leaving outer edges intact.
3: In a mixing bowl, stir together butter, garlic, thyme, rosemary, sage, and season with salt and pepper.
4: Dab the turkey dry with paper towels.
5: Rub half of the butter mixture underneath the skin and the remaining half over the skin.
6: Season the turkey all over with salt and pepper.
7: Add onion, carrot, and celery to a medium roasting pan.
8: Place a roasting rack over the veggies, and place the turkey skin side up on the rack.
9: Roast in the preheated oven until the center or thickest portion registers 165°F.
10: Let the turkey rest on a carving board tented with foil for about 10 minutes before carving.
11: For the gravy, discard veggies and pour drippings into a fat separator.
12: Measure out 1/3 cup of the fat drippings and heat in a saucepan over medium heat.
13: Add flour and cook, stirring constantly for 1 minute.
14: While whisking, pour in broth and any remaining turkey broth drippings and let cook until thickened.
15: Season with salt and pepper to taste, thinning with more chicken broth as desired.
