Remove any visible fat from the turkey including the neck and giblets (discard livers) and keep aside for stock.
Now wash the turkey properly with cold water and drain well. With the help of paper napkins, soak all the water.
Tie the drumsticks together and twist wing tips behind back. Mow spray the wire roasting rack with non-stick cooking spray.
Place the turkey in a shallow pan breast side up and then onto the roasting wire rack, and cover it loosely with foil. Roast the turkey for 2 1/2 hours in an oven at 325 degrees, basting with pan juices.
Melt the butter in a large saucepan and cook the onions with salt and pepper over medium flame for 15 minutes.
Pour in the cranberry sauce and mix the sugar, stir it well and bring it to boil.
Now reduce the heat to slow and simmer, stirring occasionally, for about 10 minutes.
Now remove the foil and glaze the turkey. Roast it for another 1/2 to 1 1/4 hour or till the temperature of the thigh becomes 180 degrees.
Then remove the turkey from the oven and allow it to stand for 10-15 minutes before carving.
The cranberry glazed roasted turkey is ready to serve.