Things You'll Need
Reheating spaghetti in the gentle ambient heat of the oven produces a finished dish uniformly heated from edge to edge and top to bottom -- without any surprise cold spots. You can take frozen spaghetti straight from the freezer to the oven without thawing it first, because it reaches the safe minimum internal temperature for eating -- 165 degrees Fahrenheit -- in less than two hours. The U.S. Department of Agriculture says this is the maximum amount of time food can safely be at a temperature range between 40 F and 140 F.
Baking Frozen Spaghetti
Heat the oven to 375 degrees Fahrenheit. Take the spaghetti out of the freezer.
Remove the freezer wrapping or lid from the frozen spaghetti. If the spaghetti is in a glass baking dish, transfer it to a metal pan as cold glass may crack when placed in a hot oven. Cover it with aluminum foil and place the spaghetti in the oven.
Turn the pan 180 degrees after 30 minutes of baking for even cooking. Insert an instant-read thermometer into the center of the spaghetti. A 1- to 1-1/2-inch-deep dish of spaghetti should heat to about 165 F after 1 hour. If not, continue to bake it, checking it every 15 minutes until it reaches the proper temperature.
Remove the spaghetti from the oven if it doesn't have a cheese topping. If the spaghetti has cheese and you wish to brown it, turn the oven broiler on and cook until the cheese browns; check it often to prevent burning the top. Serve the spaghetti hot.
If the frozen spaghetti has no sauce, cover it with aluminum foil and bake it for 30 minutes at 350 F, or until it reaches 165 F.
To thaw frozen spaghetti before baking, transfer it from the freezer to the refrigerator on a plate lined with paper towels. Thaw the spaghetti overnight then bake it in a 375-F oven for 45 minutes, or until it reaches 165 F in the center.