Martha and her mother prepare their family recipe for meatloaf.
Heat oven to 375 degrees. Place bread in the bowl of a food processor fitted with the steel blade; pulse until fine crumbs form. Transfer to a medium bowl, and add ground beef.
Place onion, garlic, celery, carrots, and parsley in the bowl of a food processor fitted with the steel blade; pulse until fine. Add to meat mixture, using hands to mix well. Add egg, 1/2 cup ketchup, 2 teaspoons dry mustard, salt, and pepper; use hands to combine thoroughly. Place in an 8 1/2-by-4 1/2-by-2 1/2-inch loaf pan.
Combine remaining 1/2 cup ketchup, remaining teaspoon dry mustard, and brown sugar in a bowl; stir until smooth.
Brush mixture over meatloaf; place in the oven with a baking pan set on the rack below to catch drippings. Cook until a meat thermometer inserted in the center reads 160 degrees, about 90 minutes. If top gets too dark, cover with foil, and continue baking.
Many recipes use only beef, but you can add veal and pork for a more tender loaf. Use an ample amount of breadcrumbs to prevent it from becoming too dense. Add finely chopped vegetables to lighten the texture and add flavor; try a combination of garlic, onions, carrots, celery, and parsley. Many recipes also call for ketchup, which lends a sweet and tangy taste to the finished meatloaf.