How to Make It
Preheat the oven to 425°. Put a baking rack on a large rimmed baking sheet. Using sturdy poultry shears, cut along each side of the turkey backbone and remove it. Flatten the turkey with your hands and put it breast side up on the prepared baking sheet.
In a small bowl, using a fork, blend the butter with the lemon zest, 1 tablespoon salt and 1 tablespoon pepper. Run your fingers under the breast and leg skin to loosen it, then spread the butter under the skin and over the breast and legs. Brush the turkey all over with olive oil and season generously with salt and pepper. Brush the garlic heads with olive oil and arrange cut side down around the turkey.
Roast the turkey and garlic for about 1 hour and 20 minutes, until an instant-read thermometer inserted in the thickest part of the turkey breast registers 160°. Transfer the turkey to a carving board and let rest for 30 minutes. Transfer the garlic to a platter. Pour any pan juice into a bowl and skim off the fat.
Carve the dark meat: Using a large thin knife, cut through the skin that connects one breast half and one of the legs. Pull the leg away from the carcass to expose the ball joint (the joint that connects the leg to the body) and then cut through the joint to release the leg. Cut between the thigh and drumstick to separate them. Put the thigh skin side down on a work surface and, using the tip of your knife, cut around the thighbone to remove it. Flip the thigh meat skin side up and thickly slice the meat across the grain. Transfer the thigh meat and drumsticks to a platter and tent with foil. Repeat with the remaining leg.
Carve the breast: Using a large thin knife, cut downward along one side of the breastbone, using your other hand to help pull the breast half off the bone in one piece. Transfer the breast half to a carving board and then repeat the process to remove the other breast half. Thickly slice the breast halves crosswise and transfer to the platter. Serve the turkey with the roasted garlic and pan drippings.