How to Make It
In a bowl, blend the fennel seeds, garlic, chopped oregano, sage, rosemary, thyme, coarsely ground black pepper, lemon zest and crushed red pepper with 1 stick of the butter.
Put the turkey on a rack set over a flameproof roasting pan. Using your fingertips and starting at the neck end, carefully loosen the skin over the breast. Spread all but 2 tablespoons of the spiced butter under the skin in an even layer over the breast. Spread the remaining 2 tablespoons of spiced butter all over the skin. Refrigerate the turkey uncovered overnight.
Preheat the oven to 425°. Rub the olive oil all over the turkey and season with salt and pepper. Roast for about 1 hour and 45 minutes, until the turkey is golden and an instant-read thermometer inserted in the inner thigh registers 160°.
Transfer the turkey to a cutting board. Carefully tilt the turkey and pour the cavity juices into a medium bowl. Let the turkey rest for 30 minutes.
Meanwhile, pour off all but 1/4 cup of fat from the roasting pan. Add the flour and set the roasting pan over low heat. Cook, stirring, until the flour is golden, 1 to 2 minutes. Stir in the broth, turkey cavity juices and oregano sprigs and bring to a simmer, scraping up any browned bits. Cook until thickened, 4 to 5 minutes. Whisk in the remaining 3 tablespoons of butter and the lemon juice and season with salt and pepper. Strain the gravy into a gravy boat and stir in the parsley.
Carve the turkey and serve with the pan gravy and caramelized lemon halves.
To caramelize lemon halves, sear them cut side down in a hot cast-iron skillet until browned, about 3 minutes.