Wash your hands well with soap and warm water for at least 20 seconds.
Thaw onions and peppers in refrigerator overnight and drain.
Mix ground beef, onions and peppers, egg, cracker crumbs, milk, ketchup, mustard, salt, and pepper together in a medium mixing bowl. Once all ingredients are mixed, form a loaf and place in a baking dish just large enough to hold meatloaf or a 9 x 5 baking dish.
Place the meatloaf in the oven and cook for 40 minutes.
Drain any liquid off the meatloaf before adding the sauce.
Mix ketchup, chili powder and garlic powder in a bowl. Top meatloaf with sauce and cook for an additional 20 minutes.