Buffalo Roasted Turkey with Blue Cheese Sauce

1. 1Combine the measured salt, celery seeds, and pepper in a small bowl and set aside.
2. 2Remove the turkey’s giblets and neck from the cavity and discard or reserve them for another use. Remove any plastic or metal holding the legs together. Pat the turkey dry inside and out with paper towels.
3. 3Rub the salt mixture all over the outside of the turkey, place it on a rimmed baking sheet (do not cover), and refrigerate for 12 to 16 hours.
4. 4Heat the oven to 450°F and arrange a rack in the lower third.
5. 5While the oven heats, season the cavity of the turkey with salt and pepper and place the onion pieces inside the cavity. Wind a piece of twine around each leg once and then tie the ends together. Tuck the wings back and underneath. Place the turkey breast-side down on a roasting rack set in a roasting pan.
6. 6Roast for 30 minutes. Add the water to the roasting pan and roast for 30 minutes more. Meanwhile, place the hot sauce and butter in a small saucepan over low heat and stir until the butter is melted and the mixture is combined. Remove from the heat.
7. 7Reduce the oven temperature to 350°F. Remove the pan from the oven and, using two wads of paper towel to grip the turkey, flip the bird onto its back. Baste the turkey all over with some of the warm butter–hot sauce mixture. Continue to roast, basting with the sauce every 15 minutes (rewarm the sauce as needed), until a meat thermometer inserted into the inner thigh registers 165°F and the juices run clear, about 45 to 90 minutes more. Remove the turkey from the oven and let it rest for 30 minutes before carving. (If you have any basting sauce left over, discard it.) Meanwhile, make the serving sauces.

For the serving sauces:

1. 1Place the hot sauce and 8 tablespoons of the butter in a small saucepan over low heat and stir until the butter is melted and the mixture is combined. Remove from the heat and rewarm as needed when ready to serve.
2. 2Melt the remaining tablespoon of butter in a medium frying pan over medium heat until foaming. Add the onion, season with salt and pepper, and cook, stirring occasionally, until softened, about 6 minutes. Meanwhile, whisk the water and cornstarch together in a small bowl; set aside.
3. 3Add the cream to the pan and bring to a simmer. Reduce the heat to medium low and, while whisking constantly, add the cheese 1 piece at a time, letting each piece melt before adding the next. (If you add the cheese too quickly or stop whisking, the sauce may break.)
4. 4Stir the reserved cornstarch mixture, and then whisk it into the cheese sauce. Increase the heat to medium and, whisking occasionally, bring the mixture to a simmer. Taste and season with salt and pepper as needed.
5. 5Remove from the heat and transfer to a serving dish. Transfer the spicy butter sauce to another serving dish and pass both sauces with the carved turkey.