Both revered and despised, meatloaf practically has its own chapter in the canon of American cuisine. Instead of baking meat and grease bits onto the pan by cooking it the traditional way, you can cook meatloaf inside an oven bag and cut down on cleanup time. Perhaps the best advantage to oven bags is they help keep moisture in so you can use leaner meats to make a healthier meal. Although cooking in a plastic bag sounds dangerous, oven bags can withstand the heat of the oven, helping you deliver a moist meatloaf to the table every time.
Combine your choice of ground meats in a large mixing bowl along with optional spices and diced vegetables such as onions and peppers. Include eggs, bread crumbs or both to bind the meat and other ingredients together. As a general rule, use one egg for every 1 to 1 1/2 pounds of meat and equal ratios of dried bread crumbs and meat. Mix all the ingredients together just enough until well incorporated.
Shape the meatloaf mixture into a free-form loaf. The amount of meat and other ingredients you use determines the size of the loaf, which determines the size of the pan and bag needed to cook the meatloaf.
Add 1 tablespoon of flour inside the empty cooking bag and twist the top closed. Shake the bag until the inside is evenly coated in flour. The flour encourages the grease and juices that drain from the meatloaf to bubble like a gravy, which prevents splattering that can cause the bags to burst.
Lay the oven bag over your baking pan. Use a baking dish such as a 9-by-13-inch casserole dish or larger -- do not use a loaf pan. Fold the bag over the edges of the pan so you can easily insert the meatloaf. Oven bags are available in sizes large enough to roast whole, large turkeys, so you'll have no trouble fitting a meatloaf inside an oven bag.
Place the meatloaf in the bag inside the pan. Gather the top of the bag in your hand and tie it closed, using the twist tie included with the oven bag. You might need to poke three or four holes in the top of the bag so some steam can escape.
Adjust your oven racks to allow 8 inches of clearance for the bag to expand while baking. This might require removing a rack, depending on the size of your oven.
Bake the meatloaf at roughly 375 degrees Fahrenheit for about 1 hour or until the meatloaf reaches an internal temperature of 165 F. Pull the meatloaf out of the oven after 1 hour and poke a small hole in the bag so you can insert a meat thermometer and check the temperature. Insert the thermometer through a vent hole if using an oven bag that requires slits.
Remove the pan from the oven and let it sit for about 10 minutes so the steam can escape. Cut the bag open and use spatulas to remove the meatloaf from the pan and bag. Set the meatloaf on a pan so excess grease can drain.
Ground beef is the star of any meatloaf recipe, but you can substitute other ground meats, such as ground turkey, pork or veal, to reduce fat and enhance the flavor of the meatloaf.