To spatchcock turkey, use kitchen shears to remove the backbone out of a whole turkey. It’s tough work but take your time. You can also ask your butcher to spatchcock your turkey for you. Some might be willing to do it for you. Remove the backbone and press the turkey flat on a large baking sheet. Reserve giblets for gravy.
In a small bowl, mash together harissa and butter. Rub the harissa butter over the entire surface of the turkey, being sure to get it under the skin of the bird as well. Sprinkle the turkey with salt and pepper as well. You can do this step up to a day in advance and keep the turkey in the fridge, wrapped loosely in plastic wrap.
When ready to roast, preheat oven to 450˚F. Slice a lemon and chop carrots and lay them in a baking sheet. Place the turkey on the baking sheet, breast-side up. Press down on the turkey so it is mostly flat. This will help with even cooking. Roast the spatchcock turkey for 30 minutes at 450˚F. Then reduce heat to 375˚F and continue to roast turkey until it reaches a temperature of 165˚F in the breast and thickest part of the leg, probably another 60-75 minutes.
Remove turkey from the oven and let rest for 15 minutes before slicing and serving.
To make harissa gravy:
Add turkey giblets to a medium saucepan with crushed garlic cloves and bay leaves. Cover with water and bring to a simmer. Simmer for at least an hour but up to two hours. Then drain stock and discard aromatics. (Optionally, you can chop giblets and stir them into the gravy at the end).
Add butter to a pot over medium-low heat along with harissa. Add flour and whisk for 1-2 minutes until an orange paste forms. Slowly whisk in reserved giblet stock in ½ cup batches. Add about 2 cups of the reserved stock to form a thin gravy. Simmer gravy over low heat for 4-5 minutes and it will continue to thicken. Season with salt and pepper to taste.
Serve spatchcock turkey with gravy and traditional sides.
Leftover turkey will keep well in the fridge for 4-5 days or frozen for longer storage.